Harold Solomon of Silver Spring, recovered from a mysterious virus that sidelined him for three weeks and cost him a chance to qualify for the World Championship of Tennis (WCT) Finals last week at Dallas, is working hard to get ready for the French Open, starting next Monday.

Solomon is entered in this week's $75,000 Grand Prix tournament at Dusseldorf, Germany. He is scheduled to play his first-round match Tuesday, but says he is "looking at this mainly as a week of practice."

Solomon, 24, was runner-up to Adriano Panatta in the French last year, the first American finalist in the most prestigious clay court championship of Europe since Herbie Flam in 1957.

"I'm not going to be concerned too much with how I do in the tournament at Dusseldorf. I'm just going to work hard every day to get in shape for the French," Solomon said by phone before leaving for Europe last week. After Dusseldorf and Paris, he will play tournaments at Brussels and Queen's Club in London, they Wimbledon.

Solomon decided to pass up this week's Italian Open, where he was disqualified last year in a line call dispute while serving for the match in the quarterfinals against No. 1 Italian Panatta, an idol in Rome, who went on to win the title. Solomon was irate, Panatta, genuinely embarrassed about this raucous bit of hometown larceny, which is not out of character for Rome's Foro Italico.

"Remember out little fiasco last year? That's why I decided to give the Italian a miss for a year," Solomon said. "I figured Dusseldorf would be a good smaller tournament, and I'd go into Paris pretty fresh. Besides, they're using the same ball as Paris this pressureless Pirelli balls used at Rome).

Solomon had bot touched a racket for three weeks until last Tuesday, when he got the go-ahead from doctors to hit for an hour.

He felt ill at a WCT tournament in Houston the week of April 16, then increasingly so at Charlotte the following week.

"They thought it was infectious mononucleosis at first, then possibly hepatitis. It's some kind of virus they still haven't identified. My sister (Mrs. Barbara Liss of Silver Spring) caught it from me and had a lot of tests, but they said they won't know what it is for a few weeks," Solomon said.

"I don't know how long I had it. I just didn't feel hungry on the WCT circuit. I was tired and I couldn't understand why I couldn't get up for matches."

In Houston, he said, he was worried because he perspired profusely. Then in Charlotte he had swollen glands and lymph nodes, and a rash all over his body. He came to Washington to consult a specialist in hematology, Dr. Jack Rheingold.

"I felt terrible and was sleeping 16 or 17 hours a day for three or four days, then it started to go away," Solomon said. "I had some liver disfunction and had to wait until that went away before I started playing again. The doctor told me to get into it easy, but that doesn't seem feasible. I'm going to have to break my butt to be ready for Paris.

"I gained six pounds when I wasn't playing - up to 144," said the 5-foot-6 Little Big Man of international tennis. "I can get rid of the weight in two days, that's no problem, but it's the timing, the endurance, the match toughness. Three weeks is a long time not to play, the longest I've gone without playing in as I can remember."

The suit filed by Bill Riordan of Salisbury, Md. against Connors, seeking 15 per cent commissions on five endorsement deals he negotiated when he was Connors' manager, was called off yesterday as the trial was about to begin in U.S. District Court in New York.

Terms of settlement were not announced, but the Associated Press reported that it was understood that Riordan could reopen his suit in another jurisdiction.

Connors did not schedule any tournament appearances until the pre-Wimbledon grass court tune-up at Queens Club the week of June 13. He had said he might not play Wimbledon if the court proceedings dragged on too long.

It is unlikely, however, that Connors will make a late entry in the French Open, the only one of the four traditional "Grand Slam" tournaments he hasn't won.

"I think I'll play Paris one day when I feel I no longer have a better than good chance of winning Wimbledon," Connors said Sunday. "With my style of play, it takes some time to adjust to different surfaces, more than most players. If I did well on the clay in Paris, I think it would hurt my chances at Wimbledon. As long as I have a chance of winning, I want to prepare for Wimbledon on grass."

Connors was asked how his WCT title, climaxing the $200,000 final playoff for the top eight finishers on the January-through-April WCT circuit, rated in his personal list of accomplishments.

"It rates very, very high, because I wanted this one bad," he said. "It was my first time in Dallas. I had heard a lot about it, and the tournament lived up to its reputation. It's incredible the prestige it has gained in only seven years.

"I was serious about it, I went to Dallas alone and all business. I wanted to play my best. I think I did, and it was good enough."

Including his $100,000 for the WCT Finals, Connors' prize money total for 1976, excluding his $500,000 guarantee for the "Heavyweight Championship" challenge match he won over Ilie Nastase, is $308,123. That toes against his annual gurantee from WCT, thought to be $750,000.

Stockton, who earned $40,000, has collected $221,049 so far this year.