Question [Q] Nexus 5 wrong s/n

I don't know how but when I reboot on bootloader my s/n wasn't 403K....., it was 060e7ed.....
Do you know how to restore into the real s/n?

LG Nexus 5 D821 (16GB)
Samsung Galaxy Note 3 N9005
Samsung Galaxy Tab 3 SM-T311
Samsung Galaxy Pocket Neo GT-S5310
Samsung Galaxy S i9000
Samsung Galaxy Tab 2 P3110
Sony Ericsson K800
Sony Ericsson K750

Speed Test

PLEASE hit THANKS IF I helped you
I am available for testing on these phones. Just send me PM
Any ideea to make my internet connection faster?