Will not dry clothes,blows cold air.

What is the model number of your unit?

I would check to see that the lint/filter isn't completely clogged up. This could make the dryer warm without allowing it to do its job of drying the clothes.
Also, is the drum spinning? If not, it could be indicative of other problems.

Is this an electric or gas unit?
murf427

2 things are needed to dry clothes. 1 is good air flow. Check to make sure that the dryer vent is not clogged or partially clogged with lint. Also make sure there are no kinks in the vent hose. With the dryer running you should feel good air flow blowing out of the outside house vent. The 2nd thing a dryer needs heat. Check to see that the dryer feels warm to hot when you reach in to tough the clothes. It is possible that the heat element has partially failed. Another thing to investigate is how well the laundry machine is spinning out the water in the spin cycle. This spin cycle is used to get as much water out as possible prior to placing the clothes in the dryer. The wetter the clothes when they come out of the laundry, the longer it takes to dry them.

some times the heating coil breaks or the thermal resistor goes bad

more than likely the heating element has gone out. if your clothes have no heat then the element is the most likely cause. you can get one for anywhere between $30 - $50. you'll need to know model and serial #'s. usually easy to replace.

The electric dryer requires 220 volts to dry clothes but only 110 volts to turn the drum .reset your circuit breaker even if it looks ok ,if that dosent work, unplug from the wall and check where the plug wire goes into the back of the dryer and look for loose or broken wires. 

Look at the bottom of your front panel and see if you can see a screw on either side about 2-3 inches from the very bottom edge of the front panel. If so take them out and pull the bottom away far enough to disengage the top of the front panel from the top panel. If this works for ya. then now you have it openened, if not repost me.

If you can turn it on and have the door open, hold the door switch in and see if you have a glow from the heating element. If not, your element is broken. That is if it is an electric dryer. If it is a gas dryer you need to check the pilot light or the thermo sensor.

A dryer needs only three things to dry clothes:
1. Tumble the clothes.
2. Blow the air.
3. Heat the air.

If your clothes aren't drying, you are missing one or more of these.

You've mentioned that the basket is tumbling. That's good. The blower is also running if the motor is turning. But that doesn't mean the air is blowing. It could be clogged up behind the lint screen, in the vent pipe behind the machine, or at the vent outside the house.

If it's blowing lots of cold air (go to the outside vent to find out) then your dryer isn't heating. This would mean some part inside the dryer has failed. If so, the first thing you want to determine is, does the ignitor glow? There's a hole at the very bottom front edge where you might see it glow. You may have to place a mirror in front of the hole to see it glow.

Write back with more symptoms, and I'll help you through the rest.