getting zoom to work

I have had Zoom for about 3 years and suddenly when i open it, it asks me if i want to connect to computer audio or phone audio, then when i connect to computer audio no one in the meeting can hear me and if they do start to hear me it is with an echo. Now, I have tried to open it on another computer thinking it was the computer that was the problem but on this computer it won't even let me start the session. Can someone help me please?