1) Are both computers part of the same Homegroup?
2) Are both computers able to share files amongst each other?
3) Have you successfully been able to play other games multiplayer via LAN?
4) Any mods installed? If so, are they the same mods and the same versions of the mods?
5) If you are using a wireless router, has this game been allowed through the router as well as your computer? Typically if you have a wireless router, there may be some ports that need to be forwarded through there as well. (The router kind of has its own firewall)...
Check those things and reply back.
1 both computers are and have been same homegroup
2 both computers can share files between and play any other game on lan
3 both pcs could connect on minecraft before without changing any settings b4
4 no mods pure vanila
5 its wireles router and same router was used to connect b4. however even if i change router, outcome is still the same.
all of these things were checked several times b4 i posted this thread.