Text messages stuck at "sending"

[AC Question]

I own a lenovo P-70A and i text alot so this has been annoying me alot. Since 2 days my texts wont go, no matter who i text, nothing is wrong with the sim, cause i ut my sim in another phone and i could send the essages there, i am not receiving any text messages either. i tried rebooting, didnt help. I got three messages since yesterday like i know who sent them and when they sent them but i got them very late and whenever i send a message it gets stuck on "sending", someone help, seriously help. solve this for me.

 

[B. Diddy]

Welcome to Android Central! You might have to try a factory reset.

 

[belovedtiger]

Ok, so how do I "try a factory reset"? Rebooting did nothing.