How do I fix this?

I'm using messenger on my sister's laptop. I haven't use the messenger on this laptop in like a an and when I signed in, I saw that all the contacts I added from last an to this an are not on my messenger list. So I tried adding them back, but when I did they come up as blocked and I can't unblock them and their status never shows. I'm really frustrated. Anyone know how I can get my contacts back on and that their status actually shows.