has been working but now it says no service what can I do to fix it

I have a Maxwest Astro 8r tablet thur the government and has been working but now it says no service what can I do to fix it

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0