If I understand your question correctly, then these curves were generated for the denatured protein without any attempt to refold it correct?

If so, then it suggests that your protein is still retaining some structure at 2M urea (keep in mind that fluorescence is a finicky tool that can respond to many different changes in the environment...not necessarily the change that you're looking for...ex. could you get a fluorescence change from a fluorophore displacing a urea molecule from the protein rather than an unfolding event?...hard to say for certain...)  I wouldn't be surprised if your protein still has some tertiary structure since much higher concentrations of urea are typically used to unfold and resolubilize other proteins.  My only concern if you're proceeding with this would be whether or not that structure that your protein still possesses is along the correct folding path or if it's along the path to misfolding and aggregation...best to just try refolding and find out in my opinion...

Hello James

Actually first fig is of 2M urea denatured proetin and the second one is of refolded one.

Based on that, it looks as though you may have succeeded in refolding your protein.  The Tm increase that you see from the top figure to the bottom figure suggests that you have added structure to your protein from the refolding protocol.  Unfortunately, thermal denaturation cannot definitively tell you that your protein is folded properly, it just provides your with a means of screening multiple conditions for refolding.  If you have a functional assay for your protein of interest I would rely on that at this point.  CD spectroscopy could be a nice alternative if you don't have a functional assay for the protein.