For some reason the domain is not detected by the PC, other computers in the network work fine, the account is not disabled but the previous logons got deleted.
Is there a way to access this PC or do I need to format it?
Is the computer using disk-encryption ? If yes it is next to impossible. Re-installing will be the best option.
If there is no disk-encryption you can break into the system fairly easily: Instructions are all over the internet (Google "utilman.exe cmd.exe"), but it basically comes down to:
Boot from a USB or DVD install medium.
On the first screen press Shift-F10 to start a CMD prompt.
From this prompt you can access the harddisk.
Find the utilman.exe utility and rename it. Then copy cmd.exe to utilman.exe
Not boot the computer as usual. At the login prompt invoke the "accessibility options" (normally this is utilman.exe) which will launch cmd.exe instead.
In CMD (which now runs at SYSTEM privilege) you can create a new local user or re-enable the Administrator account and reset its password.
Then you can login to the system and start troubleshooting your domain issue. First things to check are if the computers clock isn't way off compared to the domain and if the computer has a correct ip-address on the LAN.