Question : Lost network share

We seem to have lost connection to a network share.

Workgroup name is workgroup.
Two computers, first one running windows 2000, computer name is workstation1 with a fixed IP address of 192.168.0.15
The second computer is running windows xp, computer name is workstation2 with fixed ip address of 192.168.0.20

Have a vigor 2600 plus router with IP address of 192.168.0.1

The C: drive on workstation2 is shared as work2. Workstation1 has had this as a mapped drive for ages working just fine. But as of yesterday it seems that we just cannot connect anymore.

Can ping each workstation from each other and can ping the router all by IP address. Cannot ping via computer name. I thought it might some sort of dns issue but then thought i could re-map a drive using \\192.168.0.1\work2 and this would solve it. But this did not work, although please correct me if this is wrong.
Cannot see the other computer via browsing the network on either one.

I am now a bit lost as to what i can try next so your help would be much appreciated.

Answer : Lost network share

1. make sure you are trying to map \\192.168.0.20\work2, not \\192.168.0.1\work2 as you stated.
2. check if workgroup is really the same on both PC. Just in case
3. restart both computers
4. check subnet mask on both computers. I believe it should be 255.255.255.0
5. try to remember if you have changed something in Windows or installed anything yesterday or few days before that. Most problems arise after changes