New hard drive wont work please help me :(

Did you restore from a complete backup or did you reinstall the OS?

Reconnect the Data and power connectors to the HDD, may not be making good contact
and also unplug and plug back in the HDD cable at the MB end just incase it came loose.
If that does not work, then:
Disconnect your HDD and see if you can boot to a DVD (ie insert your windows installation disk.

i didnt restore backup because its a 2nd hand pc on the old hdd it started up but i didnt know the pass word i tried to bypass it with the admin password but i didnt know that either so i bourght a second hand hdd from a well known shop called cex its and exchange store and i dont have a windows installation disk i dont know where to get one from either  

Well you are gonna need an os disk . you can get one online for about 99 .00. Stab that in and reboot and follow instructions

i dont have that kind of money

Where is the copy (installation) disk for your OLD/broken HDD??
Unless you have it, or at least the "key" you are kind of stuck between the Rock and a hard spot.

http://www.ubuntu.com/

i dont have one of them either and whats the key ??

The Key is the XXXXX-XXXXX-XXXXX ect that you must enter before activating windows