I have a big crack in door and I need to fix it, it's about 10cm long and a little deep but not to the point where it's to the other side of door.
Also need a picture. I fix a lot of busted doors under various financial circumstances I often use bondo especially for exterior doors or even joint compound or wood putty on interior doors depending on the wood grain pattern of the door whether it be smooth or textured makes a great deal a difference when it comes to making a nice unnoticeable finished product. Priming the finished patch is a must in order to not have a dry spot look in the paint you can use a multi tool with a sanding pad for best results in fine sanding any contours that might be in the area of the patch. Of course if its too far out of shape your best option would be to replace the door if it is within your budget.