why is my form downgraded and how can restore it

I have checked your forms and they seem to be working fine, I have also checked your account and you do not seem to have reached any limit. 

The limits that are applied and the ones why your forms can be disabled are these. 

The submissions limit: Each submission that you receive will increase the counter, as you have a free account you are allowed to received only 100 submissions per month. 

The view limit: Each time that you load your forms this counter will increase, does not matter if you do not submit the form, only with the fact to load it will increase the limit, views on preview mode also count, a free account has 1,000 views per month. 

Please, read this post about the view limit: https://www.jotform.com/blog/191-Announcing-Pricing-Modification-Form-View-Limits. 

The upload space: This is increased each time that someone uploads a file and submits your form, on a free account you only have 100 MB of available space, this can be cleared by deleting your submissions with uploaded files. 

I would suggest you to integrate your form with a third party service such as Dropbox or Google Drive.

Payments per month: This is a limit only for free accounts, you are allowed to receive only 10 payments per month when using a free account, this limit is lifted when upgrading to a paid account.

 The submission and view limit can not be cleared, once you have reached one of this limits then your forms are disabled and enabled the first day of the next month, these limits are reset the first day of each month. The same with the payments per month on free accounts. 

The upload space could be cleared by deleting the submission, this is why I provided the links to integrations above. 

Hope this information will help you.