Hi janineharrison,
If by PC you meant Windows OS, have you tried the following steps:
1. Go to C:\Program Files (x86)\Common Files\Adobe AIR\Versions\1.0
2. While holding the “Ctrl” key, select the Adobe AIR Application Installer.exe -> Right click on it -> Run as Administrator. Do not take your finger off the “ctrl” key until you see the window open up.
3. Select and open the AIR application to be installed.
Thanks!