I take lorazepam already for 2 years.its for anxiety and now i feel very nervous.i have fast heart beating.does it have to do with the medication?

It has to do with : Anxiety. If you have been taking a lot of Lorazepam and miss doses you can have withdrawal symptoms and that will cause anxiety and rapid heart. Also it could be just that you are having worsening anxiety symptoms and you need to have your treatment changed. First thing however is to see your doctor to make sure it isn't something else. This experience is common to people with anxiety.

Best for short term: Long term, generalized anxiety may not be what that drug is best for. I'd recommend a therapy where you can learn how to deal with your feelings along with the support of a medication to help you be calm enough to learn well. Talk with your doctor for a possible change - don't do it on your own! and ask for a referral to a psychotherapist to work on issues together with. Best!