Booted up my desktop the other day and it smelt like burning metal. Restarted it and went to login. None of my usb ports are working. There for my mouse and keyboard won't work and im stuck on the windows 7 login screen. Is there anything i can do to fix it or is my motherboard fried?

Probably a fried power supply. What is make and model of power supply?

Was there a lightning storm or power failure, before you started having issues?

If it turns on and brings me to the widows login would that still be the power supply?
My power supply is a corsair tx750

A burning smell is usually the power supply, motherboard or vid card...but it could also be a bug that crawled in there and got electrocuted.

If you don't have some spare parts to test with (by swapping), the easiest thing may be just take it to some little computer store that you trust and pay them ~$50 to check it out for you.