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I do not have time-machine backup, so probably will not be able to sort it out this way.
I did upgrade Java and is working normally now. Java was the problem in the first place which is why I upgraded to Mountain Lion.
I have since heard from someone else that uses the bridge website I use that they have had the same problem with their imac and mountain lion and they have had to go out and buy a windows laptop with windows 7 on it, because windows 8 does not support Java.
Really loathe to buy a new laptop when perfectly happy with my iMac. Seems to be that it an apple problem with this particular website. I have sent an email to the people who run this website to see if they have any answers, not hopeful.
As far as I am concerned, Mountain Lion compared to Snow Leopard is useless, so unstable, wish I had never installed it, but Apple would not support the old Java version and blocked it on my iMac.
Anyway thanks folks for your comments, always helps to hear what you say.