If you can still access the admin email, use Lost your password? - a reset link arrives within a few minutes. Check spam, and make sure WordPress can send mail (see the SMTP article below).
Otherwise, reset it from the database:
- cPanel → phpMyAdmin → select your WordPress database →
wp_users. - Open your admin row, click Edit, and replace
user_passwith a new password. - In the Function dropdown next to it choose MD5, then Go. Log in with the plain password you typed.
After logging in, WordPress re-hashes the password to the modern format on first use.