Click on the Start Menu, and Find, Find Files/Folders. Search For
"yourmapname.bsp"
If your map name is long, check this example:
Map Name: Unbreakable.bsp
Search Key: Unbrea~1.bsp
ok, once found make sure it is in your Half-Life, vALVE, Maps directory.
If doesnot work Try this
Another way to check this is to right click on the half-life icon and add
this to the end of the target line " +map yourmap.bsp
anyways if its not there then check your worldcraft/hammer Setup guide(found on this site in the tutorials) and make sure you have the correct folder that the compiled maps are to be placed in (described above)
If none of this happened, and your bsp files are all in the correct locations/directories, then copy and paste your map into a new map and recompile, using a short and to the point name like- map1.bsp
Anyways gotto go, times up.