problem with network needs to be repaired lg-g3 d885 topic

I wanted to fix internet network on 4G so from dailpad I enterd

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which is advanced way for modifing on mobiles settings, but once I enteren on:
LTE-ONLY> Modem Setting > LTE Band Selection
and by fault I chose on a band(don't know which one) then the 4G is refusing to connect at all. <<<-------problem starts from here
I tried to repair it by choosing these bands: (band3=1800Mhz & band40=2300Mhz) sence it's our bands here in Saudi Arabia for STC company, but it didn't work.
In my city the only ban activated is 40=2300Mhz.
Do you have any solutions? let formatting be the last solution.
if I upgraded to lollipop would it solve the problem?
LG-G3-D885 kitkat