My number keys have suddenly stoed working only 5 6 and0 work also the letter rhyming with tea won,t work and the backsace button

Yes, yes, and yes.
You may view/download a copy of the manual at Owners Manual User Guide for Sharp el 531x scientific calculator
You'll find examples of exponential and logarithmic calculations in the second column of the second page and the memory instructions in the fourth column of the first page.

This is how to store a quickdial number on the Opticom B300

1. Lift up the handset.

2. Press the STO button (for 'Store')

3. Key in the full number you want to store, e.g. 01234 5678910

4. Press STO again

5. Press one of the numbers on the key pad that you want to be the Quickdial number, from 1 to 0

6. Press the MEM (Memory) button.

7. Replace the handset in its cradle.

8. The Quickdial number will now be stored and you can call it by lifting the handset (or pressing the speakerphone button) and then pressing the MEM button followed by the single number you chose.

I can't find the user guide either, but here's how to create a quickdial number on it:

1. Lift up the handset.
2. Press the STO button (for 'Store')
3. Key in the full number you want to store, e.g. 01234 5678910
4. Press STO again
5. Press one of the numbers on the key pad that you want to be the Quickdial number, from 1 to 0.
6. Press the MEM (Memory) button.
7. Replace the handset in its cradle.
8. The Quickdial number will now be stored and you can call it by lifting the handset (or pressing the speakerphone button) and then pressing the MEM button followed by the single number you chose, e.g. MEM then 3.

Rather than pressing the = key, press the "Sto" key to assign a value to a letter. eg. "12 [Sto] n ".

In order to store a number in your calculator, press "STO->" and enter a letter by pressing ALPHA and then whatever key has the letter you want on it. For example, pressing STO->, then ALPHA and then the MATH button will store whatever your previous answer was in the letter A. Then, anytime you enter the letter A into a calculation, your calculator will use the value you stored in the calculation.

Example:
Type 5 then ENTER.
Type ' (which is next to the STO button)
Press the alpha button (under the ENTER button) to type a letter or press it twice to put it in "alpha lock". Press it twice for this example.
Type F I V E then ENTER.
Your screen should look like this:
5
'FIVE'

Press the STO button.
To recall the number, press the VAR button. You should see the variable "FIVE" that you just created. Press the corresponding gray button that is under your variable. This will give you your number.

how do i store a phone number on memory

I just checked this out.
1. Press STO
2. Key in the number
3. Press STO
4. Press MEM

Keyboard is definitely bad, all kinds of keys typing other things on the screen is never a good thing.

sounds to me like somebody spilled something on the keyboard. You can try uninstalling the keyboard and putting it into another usb port to make sure the other usb port is not bad but I think the keyboard is shot honestly.