toshiba laptop model A135-S2286

Help me please. My notebook type is Tosiba A135-S2286. When i switched it on it was blocked, meaning that it is asking me a password. my laptop started that probelm since i was able to turn it off incorrectly. my laptop was brought in US with my brothers frend. and they sell it to us. can u help me on this problem?? can i reformat my laptop in order to use it again or should i need the password that is being ask to me when i open it before i can format it??