Hi
Found this: (you didnt say what size tab it is)
For Tab 2 7.0 users: Boot your device into Recovery mode: press and hold Volume Up+Power buttons together for a few seconds till the screen turns up.
For Tab 2 10.1 users: To boot your Tab 2 10.1 into Recovery mode, hold Volume Down+Power buttons till you see Samsung logo with device name and then release the Power button. When you see 2 icons, release the Volume Down button too. Use the Volume Down key to navigate between the 2 icons and Volume Up to select it. Highlight the the left icon (box) and then select it using Volume Up to enter recovery mode.
In Recovery mode, use the volume buttons to navigate and the power key to select an option or file.
Roger