erased adobe by mistake how do i reinstall

This is a puzzle. Export PDF isn't an app, so it isn't on your computer, and you can't delete it and there is nothing to reinstall. Perhaps it was Acrobat Reader you were using, and you need to reinstall that. (Reader has buttons which can talk to ExportPDF).  If you are offered a free trial, you are trying to install Acrobat Pro - and your ExportPDF license doesn't cover that. Acrobat Reader is here -- http://get.adobe.com/reader

1st, unless you went through the steps to deactivate and UN-install, you likely have broken program history on your computer, so you should clean away all vestiges of the program https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html

2nd, go to your account to verify what you are going to install https://account.adobe.com/products

3rd, do a fresh install Cloud Manager to install all programs https://www.adobe.com/ie/creativecloud/desktop-app.html
https://community.adobe.com/t5/get-started/how-to-activate-your-adobe-software/td-p/9636861?page=1