After configuring my Computer for PXE installation (as a Server). I have only one working internet connection via my home Wifi. The configuration was followed by PXE Install server Community help. Actually i can connect my computer to other routers too but i have no internet connection. How is it possible? Any ideas how can i remove the PXE stuff and recover the "Factory settings" for the network?
In all probability you had to shift your client from using DHCP to using a static IP when you installed the DHCP server. While it's not technically not impossible to run a DHCP client and server on the same machine it's generally recommended to keep the machine static.
I would simply shift the machine back to using the DHCP client. It's pretty easy to go back; edit
...or whatever your wireless interface name is.