How do i get my friends to unblock me?

[CP]

So my cousin was at my house and he was pretty pissed(his girl broke up with him) and he started messageing a few of my friends(mostly females). He then started harassing them on my phone. While he was doing this i was at a basketball camp and did not come back till the next day at night but it was to late. The reason he got on my facebook and instagram is because i leave it open( i keep forgeting my password sometimes) and now lots of my friends have blocked me facebook and instagram. This happened in march break some of my friends unblocked me but lots did not and now i feel so stupid for leaving my phone there. I asked most of them why they still wont unblock me, lots said because they dont trust me or thy think i did it. I never said anything to them and they wont belileve me so what should i do??