Is there a way to reset ECU without any special tools?

The common procedure is to disconnect the battery for at least 10 minutes which will allow any charges to dissipate resetting the ECU.

As a result when power is restore the idle may have been upset and feathering of the throttle will likely be required to keep the engine from stalling.

It can take several minutes for the ECU to relearn the idle position as you are feathering the throttle.

When reset the engine parameters are reset to factory new. The driving and shift points will also have to be relearned and can cause unexpected stall and hard shiftd as the drive parameters are relearned.

Hope thid helps? http://www.technomotive.com/theory/myth/ecureset.htm