Mongoose Threshold 2nd hand The front quick release lever of my Mongoose Threshold is missing or broken. 

I don't know the year of the bike and do not know how to determine it. There is a sticker that says ATB4130, another one that says "All Terrain" and 32" size. The tires are 26"  

Can I just buy a new skewer, or just replace lever? How do I know skewer size to buy or can I repair what I have?
The quick release lever is standard and you should just be able to pick one up second hand or from your local bike shop.  Make sure you get the one for the front and not for the rear.