There are too many examples to name. A lot of classical music was written for a specific performance, was heard once and never again. Other music was written and never performed in the composer's lifetime. Even music that was considered "popular" often only reached a small proportion of the population.

To take JS Bach for example. He composed for a very specific (small) audience and rarely published his works for consumption by the general public. It wasn't until Mendelssohn started performing his works over 100 years later that his works were rescued from obscurity. (Library of Congress: Mendelssohn: Reviving the works of JS Bach)

A good example is Bach's Brandenburg Concertos. These were written about 1721 for the Margrave of Brandenburg. He never performed them. In fact the concertos were forgotten about until the score was discovered in 1849 - 128 years later (Boyd, Andrew: The Brandenburg Concertos 1983). Even then, it was rarely performed and the public knew nothing about it until the Busch Chamber Players recorded the Brandenburg Concertos in 1935 (Classical Notes: The Brandenburg Saga).

It then became suddenly popular, further recordings and performances started happening regularly. There are now about 60 available recordings (ArkivMusic: Brandenburg Concertos) including one (by Karl Richter) that was sent into space in 1977 aboard the Voyager spacecraft as part of Earth's greeting to the rest of the Universe.(NASA: Music from Earth)