@jan, yes i’ve reviewed the links and cleaned all the files, changed admin password but not 100% sure if my site will be save as it keeps on getting infected every week. I’ve below listed plugins installed and updated
awsom-news-announcement
event-calendar-3-for-php-53
improved-include-page
nextgen-gallery
wp-simple-paypal-donation
do you think any of them above may cause the hacker to inject code into my site?