Welcome to MR, Marion.
I'm sorry you are having a problem with your Reader. Have you solved it yet?
You said you have a "plug adapter". Is that the wall (mains) charger? Did you charge using that one?
You need to make sure that it is fully charged before doing the reset.
The Hard Reset instructions are in the MR Wiki (see at the very top of this page) and this is the
link to some Trouble shooting information and
the 600 Hard Reset instructions.
Please let us know if you were able to solve the problem and just ask if you would like additional information.