Is there a reset button on my Samsung Galaxy tab?
If you could specify the exact model of your Samsung tablet,then you'll get correct method to reset your tablet.
If your tablet is working,i.e. can boot,you can got to Settings menu to reset your device.
There isn't a reset button per se, but you can reset the tablet by turning it off, holding the Volume Up button and briefly pressing Power. At the recovery menu, simply select the wipe data/factory reset option using the volume buttons to move the selector and pressing Home to make your selection. This will return the device to its out-of-box condition including the deletion of all of your data and apps you have installed yourself.
If you simply want to do a hard/cold reboot of the device, simply hold the power button until it turns off. Wait a couple of seconds and press the power button to turn it back on.