Earlier this evening I Jail broke my iPad 4.2.1 version and then removed it after the difficulties I had understanding it. After removing it I restarted the iPad and found that the Safari web browser would not start up. I never had this problem before and during the Jail break but since removing it Safari wont work.
I would be very great full to anyone who could offer help or advice.
Thanks

I am not sure how you removed the jailbreak. Can you explain? It sounds as though you haven't done it properly since Safari (which is moved as part of the jailbreak process) will only work if the iPad is booted in a pwnd state (using redsn0w). To boot the iPad in a jailbroken state you must run redsn0w and select the check box which says "just boot tethered for now". You must do this EVERY time you reboot your iPad. This is why it is known as a tethered jailbreak.

To properly remove the jailbreak you MUST do a full restore to stock 4.2.1 through iTunes.
Then you should find that everything will work as normal.
Hope this helps.