My AEG T86590IH dont heat

Kostas Damianos , check your vent first. Make sure it is not obstructed. There are many reasons why it may not work. A few are:

An open fuse/breaker in the house fuse panel. Check your outlet to make sure that you have 240 V on that. Use proper precautions and tools when doing so.

An open thermal fuse in the dryer, or a burned out heating coil. For that you will need a multimeter to check.

Open switches which can include the heat selector switch mounted on the console panel, one of the thermostats mounted in various locations as well as the motor switch and of course the timer or relay on the control panel. What have you checked thus far. Post some images of the back of your dryer with the cover removed and showing the layout of it.