mx records missing

[perfectpol7]

i am running linux ubuntu mail server, over the weekend emails stop coming in or going out. i dig my server from the server itself and i am get this results

perfectpol@mycompany$ dig mycompany.com mx
;; global options: printcmd
;; connection timeout; no server could be reached

then on a window workstation the results of nslookup is
server: mycompany.com
address: 179.a.a.6
***mycompany.com can't find mx: Non-existent domain

contact my ISP and said the problem lays with local, since my server does host the emails. (by locally mean host them at my company server)

I suppect that mx files have been corrupted or delete. How then should i resolve this, firstly I am new to the company and not all that good in linux. All the server is in command line. I tried to view the /etc/resolv.conf and it was blank. HELP.

thanks

[jledhead]

do you host your own DNS? not talking about internal dns either. whoever hosts your dns needs to update the mx records.