You used opera mini 4 and see bangla language..First u open opera click Menu go to Tools
click settings Then check the Mobile view box then Save the settings..
Now go to enter address and Write "about:config"(no inverted comma use)
Here U will see option named 'use bitmap fonts for complex scripts'
Click 'Yes' for 'Use bitmap fonts for complex scripts'
Then Save the setting..and see bangla language for ur opera