Q: Every couple of months nothing happens when I turn the key on my 2004 Xterra but latter it works also seeing intermittent tempertu

This may be difficult to diagnose without additional detail, however what you are describing sounds like potentially a faulty starter relay. If you hear a clicking sound and all power shows up on the dash, this is common when the starter relay fails.

If you do not have any power when turning the key, start with checking the ground wire (black cable) on your battery to be sure the car is getting power.

As to the intermittent temperature fluctuation, this may be a result of a bad thermostat (very common) or faulty cooling fan relay.

I would suggest having a certified expert, like one from YourMechanic, come to your home to diagnose your starting and temperature issue for an accurate repair.