Problem with LaTeX generating pdf?

[philip041]

I'm not sure where to have put this question I hope it is in the right place. I have big problem with LaTeX..

I have been writing a document for a while and recently when I click the build and view button it shows this error

[DocOpen(%bm.pdf")][FileOPen(%bm.pdf)]
Cannot execute the command

nothing comes up.

Restarting doesn't help. Also when I have managed to see a pdf, (don't know how), it doesn't shows changes I made?

Help!

 

[Pythagorean]

there's a CS forum here that has a programming subforum in it:

https://www.physicsforums.com/forumdisplay.php?f=188