Hopefully you're getting options to debug or end your execution.

If you click debug, it'll take you into the VB environment with the offending
line highlighted in yellow.

You can see the value of your local variables (which might be what you are using
as a subscript) in a pane at the bottom of the VBE window. Or if you hover the
mouse over the subscript, it should show you the value.

Another common way to get a subscript  out of range  is by referring to something
in a collection, with the wrong name for the item. E.g.

Sheets("A sheet")

will give this error  if there isn't a sheet called "A sheet".

If this doesn't help, you'll certainly need to post the code of your macro.
Also you'll need to indicate what's in any cells the macro  may be referring to.