Adding to Sarah’s excellent response – check if your LockBit variant has a known decryptor. In February 2024, law enforcement seized LockBit infrastructure and released decryption keys for some variants. Check the No More Ransom project.
Also, regarding your backups being on the same network – this is unfortunately common. For future reference, always maintain offline or air-gapped backups following the 3-2-1 rule: 3 copies, 2 different media types, 1 offsite.