I am having an issues with my adobe acrobat as it has stopped working and my serial number isn't working as it worked before. please help

Its Windows 8 Adobe Acrobat X Pro.

As it was working for the past 1 and an half to 2 years.

Then stopped working i have uninstalled tgen reinstalled it tge product key it worked then 30 days kater it stopped did tge same steps but now the product key is not reading it.