Help HELP! virgin mobile s2 but says sprint in the pull down menu


i recently bought a used virgin mobile galaxy s2 on ebay!

the seller still had their account on there so it was pain getting off then i noticed the phone had sprint start up and sprint bloatware. (how can tell if the phone is rooted/flashed?), this was acouple days ago, i tried sending and receiving texts but i cant but i notice alot of people are having trouble with that is there any fix? please help me!

i also most completely new to smart phones so please be gentle