Windows 7 wont startup

Hi,i'm having an problem with my 7 OS,because it wont startup correctly,yerstday i did an defrag on the system and let him shuttdown automaticly after this, but this morning i was unable to start the same, because the letter drive of 7 was moved from F to G but the system reserved stays on F like before where the OS was also F,i tried through system recovery but without sucess and many other possible solutions to startup but i got no results to this problem untill now,my question is,does somebody know how can i solve this issue,i'm using now vista,is possible if i change the letter drive from G to F will solve this or not?i let you an picture from the OS ob the computer panel,Thanks to all in advance.

How to change drive letters tutorial -=> Here

Hope this helps

Thanks for your help,but i've tried this a few minutes ago and got no results because when i want to change the drive letter ,the letter F don't existes anymore because is located on SYSTEM RESERVED{F} i get more letters but not F,and i dont now why i cannot change to F.

You would need to first change the System Reserved drive letter to something not in use (like say Drive J) and then you can assign the Windows 7 to Drive F