@tieubao , con, Fluffy thug life , You will have to factory reset your RCA 10 Viking Pro tablet if password is forgotten,(this procedure will remove all data). Power the device down completely, and then hold both the volume up button and the power button until the RCA logo appears on the screen. When the screen changes to the Android bot on his back, press and hold the power button and then press volume up once more. At this point, the Android System Recovery screen appears, with a list of options. Use the volume up and down buttons to navigate the menu and make selections accordingly. To reset the device, scroll to "wipe data/factory reset" and press the power button. Confirm the selection by scrolling down through several "no" entries until the word "yes" is visible. Highlight "yes" and press the power button. This info. supplied by link below which has more info. for you to read. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.
http://www.ebay.com/gds/How-to-Reset-an-RCA-Tablet-/10000000205245513/g.html