If you havent' changed it in the router settings, the default SSID should be on the back panel of the router itself, & your tablet should detect it as an available network.
If you have changed the router's SSID, just log into the router from your desktop/laptop PC & verify what the current SSID code is.
The better question is whether you remember the WEP/WPA/WPA2 key it needs to log into that network, & that you've hopefully made sure it's at least using WPA (preferably WPA2) for its encryption.