Magento

Static Content Re-Generate

Before deleting pub/static make a backup of pub/static/.htaccess and restore it again. otherwise your all css and js will show 404 error!

Remove pub/static (keep the .htaccess backed up and copy it again)
Remove var/cache
Remove var/composer_home
Remove var/generation
Remove var/page_cache
Remove var/view_preprocessed
Run php bin/magento setup:static-content:deploy

Product not showing on frontend

php bin/magento indexer:reindex
php bin/magento cache:clean
php bin/magento cache:flush

Admin login not working

1. Clear the admin session table from phpmyadmin. tabke name: admin_user_session

2. Unlock the admin account

php bin/magento admin:user:unlock $user

3. Update Password of the admin user:

SET @salt = MD5(UNIX_TIMESTAMP());
UPDATE $admin_table SET `password` = CONCAT(SHA2(CONCAT(@salt, 'NewP@ssword'), 256), ':', @salt, ':1') WHERE username = '$admin_user';

For Example:
SET @salt = MD5(UNIX_TIMESTAMP());
UPDATE mgsv_admin_user SET `password` = CONCAT(SHA2(CONCAT(@salt, 'Magento@123'), 256), ':', @salt, ':1') WHERE username = 'mageplaza';

Empty Output Of Magento Commands

Open bin/magento in your preferred file editor and add the following line and save:

ini_set('display_errors', 1);  // allow PHP errors reporting

Run the command again and now it will show the exact error. After debugging, remove the above error code.

Allowed memory size of x bytes exhausted

Add "add -d memory_limit=XX" in the command:

Example: php -d memory_limit=4G bin/magento setup:di:compile