You never know what you will find till you dig, I had the same
situation a couple of weeks ago, I found a compression splice that just
needed a turn. Good thing about it, it won't be hard to find or hard to
dig for that matter. If you find a crack in a plastic line and it isn't
too big one of those compression fittings could do the trick. Larger
than that, you can glue in a adequate length of pipe and use one of
those for a pipe union to join it to the existing line. Even if it is
metal, a proper sized plastic repair would work with 2 of the plastic
compression things, they work on metal too.