You could recover your SPA connecting a "vlan capable switch" to the internet port of the SPA and configure the port of the switch as a trunk with the vlan configured for error.
e.g.
SWITCH PORT 1 - trunk port with vlan 10 -----> SPA8000
SWITCH PORT 2 - access port with vlan 10 ----> PC
If you don't know the vlan id or you have trouble in this procedure you must reset the SPA to factory default:
connect a phone to fxs 1
digit **** then
73738# then
1 to confirm
Regards.