The New York Post reappeared yesterday afternoon after 56 days with a banner headline presumably addressed to itself: "WELCOME BACK!"

The Post, which broke with the New York Times and Daily News in order to settle its labor disputes and get back on the street alone, printed 128 pages yesterday, considerably more than it was printing before a pressmen's strike closed all three New York dailies Aug. 9.

Post publisher Repert Murdock made it clear he intends to take maximum advantage of his present position. The Post announced that while the other papers remain shut it will print Sunday editions "as a public service to readers and advertisers." The Post normally publishes Monday through Saturday afternoons.

The Post also announced plans to come out earlier in the day or in effect attempting to fill the desire of New Yorkers for morning newspapers. When the strike began, the Post had a circulation of slightly more than 600,000. It now plans to print 1 million copies.

The Times and the Daily News met with leaders of the pressmen's union yesterday in another attempt to resolve the issues at the root of the strike, but there was no indication that progress had been made and both sides spoke of needing at least two more weeks of negotiations.

The pressmen and Murdoch agreed to a settlement that leaves unchanged the basic strike issue of manpower and hours worked in the pressroom pending whatever agreement the other publishers eventually reach with the pressmen. The Post will accept that agreement with slight modifications.

William Kennedy, leader of the pressmen, likes the deal because it puts pressure on The Times and News to make concession to him so the field will not be left long to The Post, which seized the opportunity to capture advertising and perhaps circulation from its rivals.

Martin Fischbein, an assistant to Murdoch, denied a report that Murdoch plans to bring out a morning paper in addition to the afternoon Post as early as January or February. He said there has been some discussion of a morning companion to The Post, but no serious planning as yet.

The return of The Post brought different reactions from the four newspapers that began operations during the strike. One inserted the words "Sports" in its masterhead and announced it has become the New York sports graphic and will attempt to become a permanent addition to the city's news-stands.

The New York Press and The City News both plan to continue publishing until the strikes against The Times and Daily News end.

The Daily Metro, which had been advanced hundreds of thousands of dollars by Murdoch and was the subject of constant rumors that Murdoch had plans for it after the strike, announced that yesterday's was its last edition.

Its lead story was on the return of The Post, and an accompanying story was headlined: "Goodbye."