Here is where the repair button is:

Run this from your server's command line:

mysqlcheck --repair --all-databases

I had the same issue when my server free disk space available was 0
You can use the command (there must be ample space for the mysql files)

REPAIR TABLE `<table name>`;

for repairing individual tables

Connect to your server via SSH
then connect to your mysql console
and

USE user_base
REPAIR TABLE TABLE;

-OR-

If there are a lot of broken tables in current database:

mysqlcheck -uUSER -pPASSWORD  --repair --extended user_base

If there are a lot of broken tables in a lot of databases:

mysqlcheck -uUSER -pPASSWORD  --repair --extended -A

When I got this error:

145 - Table '.\engine\phpbb3_posts' is marked as crashed and should be repaired

I ran this command in PhpMyAdmin to fix it:

REPAIR TABLE phpbb3_posts;

This means your MySQL table is corrupted and you need to repair it. Use

myisamchk -r /DB_NAME/wp_posts

from the command line. While you running the repair you should shut down your website temporarily so that no new connections are attempted to your database while its being repaired.

Here is simple steps.

Go to phpmyadmin and checked that table which one crushed and then select Repair table option.

I agree with @Nican you can follow the given steps. It works some times. I have faced the same Error many times in my experience. It’s not easy to find the corrupted table in the MySQL database. Low disk space could be a major cause of this error.
You can use a command to repair the corrupted or crashed MySQL table.

# myisamchk -r <table name>

Note: r means recovery mode
If it does not work, You can go for a difficult repair.
Step 1 – Shift a database to a safe location. Step 2- Create a new empty data and index file. Step 3- Copy the old data file back onto the newly created data file
Note: You must maintain the main backup copy to recover if something goes wrong.
If both solutions do not work for you, I strongly recommend you go for a stellar repair for MySQL. This one is my best friend in my bad situations. It saves my data many times