i downloaded a new java - but having problems connecting to a remote computer. how can I go back to how my imac was configured 2 hours ago?

greetings.

is there a way to restore my iMac to how it was 2 hours ago? kinda like a system restore in PC if I wanted to revert back.. any ideas? I downloaded a new Java and I dont know how to configure it. When trying to log into my work computer it said old version of Jave not supported but earlier in the day I had no problems. Now I can't get past the launch page on my SecureID - does this sound familiar to anyone or is it foreign?? Not sure if i need to call my comapany's desktop support