If there're any mistakes in my writing please correct them for me.

I'm preparing for my first TOEFL test next month. My problem is that I can’t concentrate with the huge numbers of test samples I bought. When it comes to reading passage I thought ahh.. I don’t want to know this. It also happens with the listening test too. Speaking and Writing parts are even worse. I cannot remember any proper words to say. I forget how to write academic writing. I’m struggling. I used to be better when I was a student. My 3 years working has ruined all I studied for 20 years.

Please give me some advice. This TOEFL test is very important to me.