Inactive Infected computer - need help ASAP

My desktop is infected and need to get it fixed right away I have an online exam for school that I have to take by 11/13. Getting all kinds of weird messages such as "Hard drive clusters are partly damaged" "Windows OS can't detects a free hard drive space. hard drive error." "Failed to save all the components for the file: //system32". "Ram memory extremely low". I have a window that won't close that says System Restore but I know that it is a fake. When I click Start, then Programs it says that Programs are "empty". I hope I can fix this myself I can't afford to buy a new desktop right now. Any help will be greatly appreciated.
 
My desktop is infected and need to get it fixed right away I have an online exam for school that I have to take by 11/13.

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