Alas there is but it depends on where the lock it.. If the door opens UP and the lock is a TRI-Mark then the latch is at the bottom and you can slide under with a LONG screwdriver and depress the striker bolt.. WARNING It may fall apart when opened so have fun catching.. If it opens to the side you may not be able to do this.
The problem (IF IT IS A TRI_MARK) Note that this is specific to trimark
On the inside of the lock is a bell crank lever (Basiclly a more or less flat metal bar) the handle pushes (Down or to the side) on one end and the other end then pivots UP (or to the other side) pulling the striker bolt.
The screw is loose is option 1
option 2 is the striker bolt broke and needs replacement.
Now.. I know a shop that makes replacements for 45 bucks a pop (Senece Engineering or Seneca Machening. not sure which) Seneca SC) but.. unless the bolt is the same size as mine he does not have a pattern.