Hi zoel_222 and welcome to TSF.
Firstly we need to fix your ability to reassociate file types for programs. Please follow this
link for File Association Fixes for Windows 7. You will want the EXE one.
To fix the association for a particular file type:
1. Download the corresponding fix from the above table. (Use Right-click – Save as option in your browser to download the fixes.)
2. Unzip the file and extract the .REG file to Desktop.
3. Right-click the REG file and choose Merge. Alternately, you can open the Registry Editor and then using the Import option from the File menu, to merge the REG file contents.
Note that you need to be an administrator to apply these fixes.
Then, you will need to start a new thread in the ' Virus/Trojan/Spyware Help
' section and give then all the details
they require to help you.