Urgent help please!

I have a website that has been working fine for the past few years, I have made some changes and uploading them through SmartFTP. I have gone to view my website in my browser and most of the website is missing! I can not work it out all i have done is move things around and delete a couple of pages not a lot has been changed. It said everything was all correct.
Has anyone had this experience or can advise me on what to do please.
The program that I use to make the website is Web Page Maker.
Thank you in advance.

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