Ginbo

So, I am on mission 5. It has gotten incredibly dificult, however, because all my guns, including the RPGs, have disappeared! I did go back to try to finish the last few missions of OFP, and I wonder if that stole the guns from me, but does anyone know what to do? I heard about going back to the cutscene before the mission, but that does nothing for me! Do I just have to restart the game? I hope not. Ginbo.