If you thing that your website is hacked or infected by malware, first thing you have to do is contact your host service provider and ask them to put your website in offline or maintenance mode. Mostly the attack came from server itself. So you have to cut off your data from server. Open your .htaccess file and look for any lines of coding that look suspicious. If you find any suspicious coding, then change it.  Sometimes it will fix the problem. If that is not the problem, then take a back up of all the database and data files. (Although your website is infected, it is good to take all back up for future reference).  After that, change all database,  admin passwords and access keys.

Next scan your system and local network systems to check malware attacks. If your system is under a threat, then format and reinstall the operating system. Then check for old website back up files include data  files, database, plug-in, custom styles, everything.  If you don’t have any back up file, don’t worry. Most host service providers back up their hosting website data regularly, and if your website was infected recently, they can simply restore it to a previous point, when it was not yet infected. They can also help you to identify and fix the vulnerability that led to the problem. Then complete clean up your website data and restore the latest back up data. Make sure that back up files are clean and free of hacked, by using any online scanner or scanning software. Keep an eye on things, as the hacker may try to return. So always keep your site up-to-date, scan your system regularly and try to use difficult passwords in data accounts in order to prevent attacks again.