Couldn’t start pc due to hard disk problem.

i have two hard disk 160GB & 500GB. My OS was getting corrupted & finally got disk read error. So i gave 500GB hard disk for replacement, as it just 7-8 month old. At first I had 160GB hard disk, now I’m trying to run my PC with 160GB hard disk. Now windows couldn’t start due to hardware ditection problem. I know I’m doing something wrong but don’t know what.

CAN U PLZ TELL ME WHAT TO DO???
NOW I CAN’T ENTER IN BIOS/CMOS……..
I CAN’T WAIT WITHOUT PC FOR 7 DAYS………………
Answer #1
Possibly bad RAM?
Answer #2
Make sure the hard drive is pinned as master.
Answer #3
Are you getting any BEEPS? if so, check the motherboard manufacturer troubleshooting guide to find out what the BEEPS mean.
Answer #4
Make sure the hard drive is pinned as master.
Can u pls tell me how to check that?