Mukul,
I don't work for Upwork, but I know from reading the forums that they aren't going to talk with you about your sister's account. There is some kind of confidentiality/legal issue there, so they have to deal directly with the person who has been suspended.
The best thing your sister can do is to try to get in contact with Customer Service.
When she was suspended, Upwork sent her an e-mail. This e-mail was sent to the e-mail account with which she registered on the site. In that e-mail, there should be a link that your sister can follow in order to help resolve her issue (depending on why she was suspended, anyway. If she violated the Terms of Service there probably isn't much to be done for her). But they won't tell you anything.
Have your sister check her e-mail from the time she was suspended, even the spam or junk folders, and when she finds the suspension e-mail from Upwork, she can contact them through that.
