Welcome to Android Forums. Sorry for the delay in responding to your question.
More info is needed, but I will try my best to answer anyway.
If your phone/tablet has never been rooted (running a root exploit that gives you access to all your phones system files), then go to the settings menu and try to find the factory reset option (should be under the privacy section). If unable to even get there do to the process crashing, then you will need to get into your recovery to perform the factory reset.
For more info on how to get into your recovery (Not all Android phone recovery access is the same) and way more phone support go to your phone specific forum here at Android Forums.
Hope this little bit of info points you in the right direction. We have very knowledgeable members here that can solve your problem fairly quick.
AndyOpie150