If you have Admin privileges and you cannot run installations, it's due to one of the two reasons:
- You have a virus which prevents the Windows Installer service to start the process.
- Your Windows Installer is crippled for whatever reason and does not work properly.
In the first case, you can run an Anti-Virus search with one of the Portable versions of AV's without having to install them. In the second, running sfc /scannow from the Command Prompt should initiate a System Repair routine and check for any issues within Windows and correct them if possible.