How to reinstal system 32 in window 7 laptop

Either you have a virus that damaged the installation, or it's a hdd problem. Time to backup your personal data!
Virus: http://www.mcafee.com/hk/downloads/free-tools/stinger.a...
HDD: right click on c: in explorer, got properties / tools and run the error checking

I think there is more to your message. It probably states C:\Windows\System32\filename.dll is not compatible or something similar. Windows can repair corrupt or missing system files by using the system file checker. It must be run in an elevated Administrator command prompt. Click the start button and type CMD in the search field. Hold the left shift key and right click the entry found. Choose Run as Administrator. In the DOS window type SFC /scannow. It will tell you what it fixed and might say it couldn't fix it.

If you are receiving a message that says c:\windows\system32\system is missing our corrupted then you have a corrupted registry file.

You should be able to copy the C:\Windows\System32\config\regback\system file to the C:\Windows\System32\config\system file after booting with a CD/USB and then reboot.