Try contacting Adobe Support thru chat and ask them to reset your activations. If you only ever had one installation activated, you still have one available before you need to contact them though.
Chat support - For the link below click the Still Need Help? option in the blue area at the bottom and choose the chat option...
Make sure you are logged in to the Adobe site, have cookies enabled, clear your cookie cache. If it fails to connect try using a different browser.
Serial number and activation chat support (non-CC)
https://helpx.adobe.com/contact.html?step=PHSP-PHXS_downloading-installing-setting-up_licensing-activation_stillNeedHelp