Urgent WordPress 500/408 Fix

My WordPress site has gone down across the board—every page now throws either an HTTP 500 or a 408 timeout. No plugins or themes were added or updated recently, so the root cause is not obvious from my end... (Budget: ₹1500 - ₹12500 INR, Jobs: cPanel, HTML, MySQL, PHP, phpMyAdmin, Web Development, Website Optimization, WordPress)