sim card not detected after rooting honor 3c u 10

[AC Question]

i am new to all of this...so i would like a detailed description of how things are done
i own an honor 3c u-10 international device.it was still on jellybean until two days before my friend trid to root my phone.he used kingroot ato root.but after the root my imei is null and the sim cards are not being detected.when i am trying to flash a rom it says md5 file missing and it fails.please do help me out as soon as possible.