Leann

i have a acer aspire laptop. When i cut it on it beeps alot, and when it finally comes up it lets me put my password in. Then it goes to a black screen and gives me a message. Its logon ui.exe it says shell32.dll is missing and needs to be reinstalled, the curser works, and ctrl alt delete works but when i use that all i can do is cut the computer off when i go to task bar it flashes the message again. The only thing it will let me do is when it starts up i can hit f2 to go in the set up but i dont know anything about that stuff is there anything i can do to fix it?