ora-12514:tns:listener does not currently know of service requested in connect descriptor

ارجوا مساعدتي في حل هذا الخطأ

you have to try two things :

1- go to net manager and check the listner confugration and oracle home directory (you can open net manager from program file oracle configuration tools)

and restart your database or windows.

if your issue still there try to reconfigur your listner from net configurstion assistant .

and restart your machin.