I have a Samsung Tab 9

[Benz63]

Ive just plugged tablet into charger and it's not coming on or showing percentage what is the problem 

[johnz237]

Hi! Welcome to the Samsung Members community!

This is a bit hard to answer with absolutely no context

First,
press and hold the Volume Down and Side (or Power) buttons simultaneously until the screen goes black and the device restarts- try for 30 seconds

Maybe attempt using another charger that you know works?

How long has it been dead?

Being impossible to know exactly, if the solutions above don't work, you'll need to contact Samsung directly.

[Benz63]

The tablet is pretty new got in February but hasn't really used it.

[johnz237]

Attempt the methods I've tried.

Batteries don't like being dead for long periods of time, so be mindful. It could be that you just need to leave it charging.

Attempted what I suggested?

Absolute worse case devices have a warranty

[Benz63]

Thanks

[JAMES4578]

some other Advice, as a process of elimination check there is no Debris in the charging port, may just take a liitle time to kick in though try another charger if you can. You may though need to plug into a computer via other  Mobile Device  or TV  USB  and hold the Volume up and power keys at the same time until the samsung logo appears. it should then Boot into Recovery Mode and first option should be to Reboot system now. if that does not work there is the option to Factory Reset but all Data will be wiped.
However if no solution it may need a repair and you would need to contact Samsung Support for assistance. https://www.samsung.com/uk/support/product-help/mobile-devices/

[Benz63]

Thanks for your help got it up and running,it's charging now 🙏