I do not think that changing computer (or workgroup) name makes computer unreachable by its ip-address.
Returning a computer the previous name never recovers the same computer SID, i.e. after getting the same name the identification of computer is different.
All users in a workgroup are identified as (computer ID)\username and so, effectively, they and access to any network shared resource (service, file, etc.) under those IDs (accounts, users) were reset.
I would reboot computer after changing computer (or user/account) name and reset/reinstall anew any network shared resource (network printers, network shares, shared network services, etc.) that depend on any such usernames with corresponding reboot on any other computers.
IMO, such changes require some time to propagate and are not immediate and require up to 2 hours to be known by (sychronized at) other computers in workgroup