transmission bit torrent client in ubuntu is not working it's neither downloading nor uploading anything earlier it used to work perfectly but for some reason it has stopped working can any one help me troubleshoot this.besides my internet connection is working fine and i can browse the internet on the same machine.

1. Is your ISP blocking conventional bittorrent ports? They do this.
2. Has your firewall/router been upgraded recently?
3. Did someone shut off upnp/port forwarding on your router/firewall? Not every router handles UPNP well.
4. How do you have transmission configured to forward ports?

this is the output from the settings.json file located in the transmission-daemon directory.i think this is the main configuration file for the application.
{
"alt-speed-down": 50,
"alt-speed-enabled": false,
"alt-speed-time-begin": 540,
"alt-speed-time-day": 127,
"alt-speed-time-enabled": false,
"alt-speed-time-end": 1020,
"alt-speed-up": 50,
"bind-address-ipv4": "0.0.0.0",
"bind-address-ipv6": "::",
"blocklist-enabled": false,
"dht-enabled": true,
"download-dir": "/var/lib/transmission-daemon/downloads",
"download-limit": 100,
"download-limit-enabled": 0,
"encryption": 1,
"incomplete-dir": "/home/Kev/Downloads",
"incomplete-dir-enabled": false,
"lazy-bitfield-enabled": true,
"max-peers-global": 200,
"message-level": 2,
"open-file-limit": 32,
"peer-limit-global": 240,
"peer-limit-per-torrent": 60,
"peer-port": 51413,
"peer-port-random-high": 65535,
"peer-port-random-low": 49152,
"peer-port-random-on-start": false,
"peer-socket-tos": 0,
"pex-enabled": true,
"port-forwarding-enabled": false,
"preallocation": 1,
"proxy": "",
"proxy-auth-enabled": false,
"proxy-auth-password": "",
"proxy-auth-username": "",
"proxy-enabled": false,
"proxy-port": 80,
"proxy-type": 0,
"ratio-limit": 2.0000,
"ratio-limit-enabled": false,
"rename-partial-files": true,
"rpc-authentication-required": true,
"rpc-bind-address": "0.0.0.0",
"rpc-enabled": true,
"rpc-password": "{758ca999362896a09c5d32e4fc1eb5f03d04de1aHE28VipP",
"rpc-port": 9091,
"rpc-username": "transmission",
"rpc-whitelist": "*",
"rpc-whitelist-enabled": true,
"speed-limit-down": 100,
"speed-limit-down-enabled": false,
"speed-limit-up": 100,
"speed-limit-up-enabled": false,
"umask": 18,
"upload-limit": 100,
"upload-limit-enabled": 0,
"upload-slots-per-torrent": 14