I cannot unlock my tablet from the touch screen

Click on the link to get the solution for your frozen screen............
What You Can Do To Resolve Frozen Screen Issue On Kindle Fire HD Device

Can you explain how it's frozen? Sometimes it needs a specific (unfreeze) code but usually it's related to improperly flashed custom ROMs therefore most likely you need just restore factory settings to revive it from the glitch.

Seems like the digitizer isn't working anymore u may wanna get ur tablet examined but to quickly turn off some tablets is to press and hold the power key till it shuts off and not lock the screen

On most modern computer devices, just pushing the On/Off switch is only a suggestion and the computer can ignore it (or might not get the suggestion). Try holding the On/Off switch down until the computer turns off (that might take 5-10 seconds).

First try and hold the power button down until it switches off and then turn it back on and see if you can unlock it.
If you can't unlock it then you can do a recovery this is how
when it is switched off hold the volume up and the hold the power button until you see a recovery screen with options there you will see a option to recover.

Well I'm trying to fix a ematic tablet because it frozen

Try to reset the unit. the battery may be faulty.

my tablet needs to be caliabrated I try to touch a letter and it wont work

There is a tiny reset hole on the back of the tablet marked with a "R" near the SD card slot. Push a small paper clip in the hole until you feel it hit the button. This will reset the tablet and the touch screen will start working again once you power it back up. --Emerson m744 android tablet.