Re: I can't turn my wifi on.. when i go to the settings and open Wi-Fi, i'm unable to slide the switch. What should i do?

First you need to set Wi-Fi up.

Read here: http://help.apple.com/iphone/8/#/iph1b489c85f

Please describe if your wifi its looking dark grey . If its looking dark grey and you don't have option to turn it off i am sorry but this is very common problem on many iphone 4s . The problem is on wifi chip and you need for sure hardware repair or replace the device if its under warranty .

Tommacgr wrote:

Please describe if your wifi its looking dark grey . If its looking dark grey and you don't have option to turn it off i am sorry but this is very common problem on many iphone 4s . The problem is on wifi chip and you need for sure hardware repair or replace the device if its under warranty .

Not necessarily. While it maybe a hardware issue, until certain steps have been taken, that cannot be asserted as fact.

OP, if your wi-fi is greyed out, please use this article: iOS: Wi-Fi settings grayed out or dim - Apple Support

If that fails to resolve, then try this: How to erase your iOS device and then set it up as a new device or restore it from backups - Apple Support

Make sure to follow those steps precisely, including the part about backing up first. You'll have to backup to iTunes on your computer, obviously.