Which version of Lazarus?
Official installer, or otherwise downloaded/installed?
FPC version?
Does the IDE display any error in the "messages" window?
Does it work on a new application (menu: Project > New > Application)?
E.g. if you try to ctrl click TForm
What OS are you on, maybe ctrl click is blocked. Have you tried the keyboard ? (I think Alt + Up key / but not sure, maybe I changed mine ...)
If none of that works => try to start your IDE with an empty config
lazarus --pcp=/new/empty/folder
lazarus.exe --pcp=C:\new\empty\folder
Do the projects compile and run?