Q:

How to restore previous backup mysql db in mamp to upgraded version

I am using MAMP and tried to upgrade it to new version, 
I took backup of the db and all files from htdocs folder
(Copy pasted them as backup before uninstalling)

I installed new upgraded version of mamp 4
On copying the mysql folder back, the mysql server was not starting.
After googling, I uninstalled it again and changed the previous version of mamp 3.5, 
On restoring the db, the mamp runs however no backup data table is showing the schema and data.

A:

You can try mysqlfrm to recover your backup. 

The mysqlfrm utility is designed as a recovery tool that reads .frm
  files and produces equivalent CREATE statements from the table
  definition data found in the file. In most cases, the generated CREATE
  statement is usable for recreating the table on another server, or for
  extended diagnostics.

mysqlfrm --diagnostic mysql/db_name/ > db_name.sql

Then is just a matter of importing the .sql file
If you are using windows, the mysqlfrm Utilities is not installed by default if you are using WAMP/XAMPP. So you need to install manually by downloading it from HERE.
For more details on how to proceed check this step by step tutorial.

