I need your help on Hard drive

Hello,

I want to know how i can solve a problem am having in my PC now. I have a 2 hard drive in my computer,..one is Master (which has being partition)and the other one is slave,.and that's the place have being saving my Data and doc. Now when i restart my PC,..i can's find my F:/ drive which is the one i use to save my Data and Doc. in. Is not responding and am afraid now,..i have all my Data in that Hard drive. How can i solve this problem. Please help me solve the problem. Also i have tried putting another Hard drive at the same place the other one was,..and is working and if i put the old one there,..is not working. SO then what should i do now... I need your help.