The grand Hollywood Roosevelt Hotel, site of the first Academy Awards ceremony, reopened Thursday night following a $35 million restoration. June Lockhart, Morey Amsterdam, Richard Thomas and Rudy Vallee were among the 300 guests who attended the ribbon-cutting party at the hotel.

The 12-story Spanish colonial edifice was built across the street from the famed Chinese Theater for $2.5 million in 1927. It became a second home for celebrities in the 1940s but fell into disrepair and closed down two years ago.

Architectural details in the restoration include finely carved columns framing tapestries, hand-painted wood beam ceilings and the staircase where Bill (Bojangles) Robinson taught Shirley Temple to dance in "The Little Colonel."

"This renaissance of the Hollywood Roosevelt Hotel is more than just a renovation of one building in Hollywood," said Los Angeles Mayor Tom Bradley. "The fact that the very first Oscar awards were presented here . . . means that in 1929 it was good enough for the best. As far as I'm concerned, it still is." Vietnam Vet May Resume Fast

Gino Casanova, the Vietnam veteran who ended a 51-day fast when President Reagan agreed to talk to him about men still missing from that war, said he will go back into his bamboo cage and resume his fast if he doesn't get a firm meeting date from the White House by noon on Jan. 8.

"And this time, no water, nothing," the 34-year-old ex-Marine said Thursday in Seattle. "This isn't pressure on Reagan, it's on me. I didn't enjoy the fast experience, it's the last thing I want to do again, but this thing has gone on too far." He said he planned to begin sending daily telegrams after the first of the year, asking for a date for the promised meeting.

Casanova ended his fast Dec. 5 after a telephone call from Reagan. The veteran said Reagan agreed to a meeting within 60 days to talk about missing-in-action issues. A White House spokesman said Casanova's request was "placed in official channels," but a decision might not be reached until early January. Here's the Beef

Herbert Paul Schenck, 32, of Westfield, N.C., is having a beef with Burger King about their ad campaign, which features a vague, pitiable fellow named "Herb."

"At first I thought it was funny, but I'm getting comments from people about 15 times a day," said Schenck. Schenck told Burger King restaurant managers in the Winston-Salem, N.C., area that he's had enough ribbing. But the managers said there was nothing they could do because the commercials were part of a $40 million national advertising campaign that began last month.

Their statements moved Schenck to extend an invitation to all perturbed Herbs to write to him at Rt. 1, Box 137, Westfield, N.C. 27053. He wants them to join together to fight back through public complaints, pickets or a lawsuit.

"I want an apology and I want them to stop it, if I have to hold them hostage with a ketchup bottle," Schenck said. Chess Champ Opposes Rematch

Gary Kasparov, the new world chess champion, confirmed yesterday that he opposes an early rematch with Soviet rival Anatoly Karpov. "At this point, I consider that a revenge match is nonsense," Kasparov said in an interview with the Soviet news agency Tass.

In the interview, Kasparov condemned the sport's international chief, Florencio Campomanes, for disrupting world title rules. "Deplorably," the champion said, the rules "have not been stable in the past three years. They have been changed three times."

Kasparov beat Karpov in a 24-game match that ended last month. The rules of the match, which followed the controversial cancellation by world chess officials of his first title bid, included a clause stating that Kasparov must defend his crown in a third duel with Karpov to start next February.

Kasparov also criticized some western media for unfairly depicting him as anti-Soviet. "An attempt is made in the West to depict me almost as a dissident," he said, and to present his opposition to the rematch "as a confrontation . . . not only with the Soviet Chess Federation but with our entire socialist state." End Notes

Radio humorist Garrison Keillor has bought a house for an estimated $300,000 in St. Paul, Minn., within easy commuting distance of the fictional town of Lake Wobegon, a local newspaper said yesterday. The host of "A Prairie Home Companion," which originates in St. Paul, will be married tomorrow to former high-school classmate Ulla Skaerved in Copenhagen. Purchase of the house ended speculation by friends and associates that Keillor, upset about recent articles on his personal life, might soon leave the city. -- Lisa Serene Gelb