Hello Ionut , in your case you have 3 options :
1. Because you have a local network , you can go to a friend and install your hard drive as a slave in to his computer and he will format your drive from his operating system. (with Partition Magic , Fdisk, or other partition utilities)
2. You can boot your PC from a friend's PC (from the network) but for this to happen your network card has to have 'wake on lan' . We cannot explain how to do that because it depends if you will boot your PC from a Windows OS or Linux OS , or server , etc.
3. Borrow a CD-ROM from a friend to format your PC .