Open File Problem

Hey Thanks for reading I really need help!!

On the 24th some window pc provider started popping up and giving me problems when trying to open anything. Telling me to purchase software to protect my computer. The next day McAfee says expired. After that when i would double click on a file it would give me the open with window, with options to open each individual program. I opened firefox so I could access the internet. Every file would open this way, and when i would chose a program the majority of them wouldn't work. Just firefox. Still getting the provider pop ups, my friend tells me last night to download spybot and avast....for my firewall and spyware. So i did it and this morning i had to go from the menu bar to access my internet link, click run as and in the open with folder had to choose my provider for that file. Fortunately that worked. So I was scanning the internet on how to fix my open folders problem...ended up checking the folder options, going file tabs, adding EXE by clicking new and applying, downloaded the web address and all. Now my files won't open at all. I can access my control panel but only certain parts...some of the files won't open. Afraid to go anywhere or touch anything in case i can't open anything again. Any advice would be amazing!!!!