numbers and pages files disappeared!

Got to work today, opened my ipad air, BOOM, all my spreadsheets have disappeared. On checking pages, only the most recent files are there, older files have disappeared. Checked my iphone 6 - same as my ipad. After checking this site, I logged into icloud.com - same result. If I restore from a backup, will they come back? why have they just gone? This is really important work stuff for my own small business - why I am I paying for icloud and extra storage if my files aren't safe?? Can anyone help....? at my wits end....