When messing around repairing pc's there is always chance of problems. Sometimes medicine has side effects does it not? So backup whats important and what you want always before you get to step 1 Secondly to burn the disc image download this for free : The Official ImgBurn Website
And follow this guide to burn UBCD that you downloaded with it How to Burn with ImgBurn
So here are some simple instructions:
1. Choose burn ISO TO DISC click the "browse for file" icon (little folder icon next to please select a file) and navigate to your "UBCD4Win.ISO" file and click ok. 2. Click the "write" icon. (The button above with the disc.)
3. Once completed it will say and restart pc.
4. Boot cd how you would boot into windows disc.
Lastly and most importantly follow this it should be straight forward let me know if you get stuck
> Download the .iso file,
> Burn to disc,
> Boot from that disc,
> look for hard disk tools
> Select drive wipe on your drive
> Make sure it's says that it does a 0 erase wipe (FULL WIPE)
that will erradicate any data on the drive, then attempt to reinstall with windows disc.
Let me know how you get on and most importantly
take your time but backup first.
Oh and also with UBCD read everything and follow and you will find it easy