You left your wallet alone for a couple days, and when you take a sneak peek, there he is, not synchronizing.
So what to do? Take this following steps:
1 - Take a look at the Network Monitor, in Debug Window, of your Wallet. If there's no In or Out, test your network status.
2 - Try to reopen your wallet.
3 - Make sure that the firewall and antivirus isnt blocking it, a few antivirus mark the wallet as false-positive. Too damn sucess in my opinion
4 - Reinstall your wallet, with this "little" condition: DO A BACKUP OF YOUR WALLET.DAT, if you dont do this, say goodbye to your MXT coins.
The wallet.dat is in %APPDATA%\MXT or C:\users<username>\AppData\Roaming\MXT
To synchronize faster, download the bootstrap in martexcoin.org