I posted this here last night and it seems to have disappeared into the ether so here goes again.
I recall a film (or TV series but 99% it's a film). A guy is in hospital (special agent/spy) and he's told that he's been in a coma for several weeks. To prove it the doctor shows him a newspaper that mentions a recent political event ( a summit etc), that he was secretly supposed to either stop or intervene in. He then notices some small cuts on his hand that should have naturally healed had he been in hospital as long as the doctor told him. From this he surmises that he has been drugged and kidnapped by enemy agents to stop him interevening in this political event.
Some of your plot description is familiar. The film I recall is about an American officer who knows the D Day landing details and is caught by the Germans. They make a fake US hospital and tell him the landings were a success and he had been there for weeks. He sees the paper cut on his finger and realises they just want him to reveal the details.
Trouble is, I cannot remember the title!
I have seen this film twice on terrestrial TV but do not remember James Garner being in it. However I have just googled it and found a TV version was made and that may be the one I have seen.
I must admit that I only saw the latter part of the film (confused at what was going on), on TCM, the first half is said to be excellent, then it slips into run of the mill ww11 thriller, according to one of my (many) film books.