Hi.
It shouldn't have affected the phone at all !
Just in case have you cleaned the new sim and contacts in the phone. There's a chance they are not connecting or the 4g sim was not seated correctly.
Or a remote possibility the 4g SIM card has a fault and is just a coincidence that it happened when you put your normal sim in it.
You can pick up blank replacements at any O2 shop or have one posted to you and perform the swapmysim yourself.
Links can be provided if you need it.
Have you also tried a soft reboot of the phone and or if you have the option within its settings to 'reset network settings' then try that.
Possibly a hard reset may help but make a back up first to save your downloaded and saved data.
http://www.hard-reset.com/samsung-galaxy-s4-hard-reset.html
