How to disable 3g network on my android phone?

Settings => More networks => Mobile networks => Network mode => GSM only

Press and hold the power button and a menu will pop up. Then tap on Data network mode to turn3g off. Repeat procedure to turn3g back on again.or Check your settings here: Settings -> More -> Mobile Networks -> Network Mode -> put GSM only.hope it will work.

To disable3g:

Go to Apps->Settings->Wireless & Networks->More->Mobile Networks->Network Mode

Select GSM only.

Or In ..->Mobile networks, select 'Use only2G networks'.

To disable data:

Touch from top to bottom. Then tap 'Data' to disable it.

If you didn't the above options, you must find it

..->Mobile Networks->Data Enabled check box.