Can I file case after long time of my uncle murder

Limitation period does not apply in such case. yes, you can file FIR, provided there is good grounds to point out the guilt of the accused. 

Yes you can lodge FIR for murder if you have sufficient evidence with regard to the offence and the offender, police will base its investigation on the basis of the evidence and lead you provide to them.

The offence such as murder punishable with life imprisionment or death sentence has no period of limitation under section 468 Cr.P.C.

You need impeccable, unimpeachable, tangible and verifiable evidence to file either a private complaint or FIR after a lapse of so many years. It will definitely reflect adversely on the local police force.