ii removed thermal fuse and dryer starts up ,now I let it run for awhile and it dosen't heat up! I also checked the heating element and thermal cut off /high limit theramal fuses and they all passed continuity test what can be the issue?

Temperature control switch?

I am assuming this is an electric dryer.

You have already said you checked the thermal fuse, as well as most of the other control element. Make sure that the element reads 10 Ohms. It also should not be shorted to the case.

Next I would check to make sure you have the proper power to the unit. The machine will run properly if one leg of the 220 has failed, but will not heat. The only part of the machine that has 220v to it is the heating element.

You can either have an electrician check the outlet, or you can do the following:

Slightly pull the power cord out of the wall socket so you can see the terminals. Carefully touch your probes so you don't cross two terminals together.

Across the two terminals that are in line with each other horizontally, you should measure 240v.
Across the other terminal and each of the previously checked terminals you should measure 120v.