HardDisk crashed, Need OEM Windows 7 64 Bit home edition for installing windows on my dell N5010

Hi,

I had bought laptop about 3.5 yrs back and it was working till 2 days back.

My hard disk crashed as there were a lot of bad sectors and had to replace the disk. I have entered the windows key shown by "WindowsProductKeyFinder.exe" which i downloaded as freeware from internet. Using this key i am able to use windows, however in system properties i get info as the key is invalid and windows will expire in 30 days.

The Microsoft sticker at the back of my laptop has faded completely and nothing is readable. Presently I am out of Dell support and Microsoft support says that OEM cannot be converted to retail version and asked to contact Dell (manufacturer). Dell is reluctant to help as i am not under warranty now. My windows will expire in 30 days, is there any way by which i could make my windows not to expire or will have to buy new windows version?

Regards,

Sachin