2005 jeep grand Cherokee middle back seat belt locked how do I fix this?

I was not able to find any recalls for this issue, however I would suggest you take it to the dealer and have them check it out. If the belt has never been used or misused then this is a dealer issue and they should be able to fix it for you at no charge. If this is not a dealer issue then you will either need to have someone replace the unit or do it yourself. There is no reason to do any repairs on a seat belt, just replace the thing. This link should help you find what you need: http://www2.partstrain.com/store/?PN=4294955026&N=0&VN=4294967178+4294966246+4294966082+4294967104+4294967096&Nr=AND(universal:0)