help with "windows cannot find" and "shellexecuteex failed"

Problem: I think i have a virus but I can surf the internet and do standard functions. It wont let me change certain settings or change the administrator settings or anything like that. I download fix after fix but cannot run the exe files to repair viral problems.

Issue: When I try to open most (not all) icons or exe files I am prompted with "Windows cannot find 'xxx'. Make sure you typed the name correctly, and then try again." I have tried to Open as Administrator but get the same prompt. After downloading each fix that I find on the internet, I click on the repair exe files and get, "ShellExecuteEx failed, code 2. The system cannot find the file specified."

when i go into control panel to try and change certain settings (say the administrator settings for example) i click what i want, and nothing happens. i notice that whatever i click on has a little shield by it.

I have a Dell inspiron e5105 laptop

any help would be so much appreciated. i don't really want to pay a lot to have this fixed by someone if there is something i can try so please send suggestions my way!