deactivated account: is it possible to reactivate (within 30 days)

Hi @silke2world welcome to the community!  I found this article from Atlassian Support on reactivating your account, can you try that to see if you get your account active again?

reactivate-disabled-unmanaged-account 

Hi @silke2world 

Welcome to the community.

If the options in the link @Dan Breyen provided can't help you out, then take the following steps:

1. Open a browser in Incognito/Private mode (this is important to ensure you aren't automatically logged into the suspended account).
2. Go to the Atlassian Support: Pricing, Billing, & Licensing | Atlassian.
3. Under How can we help you?, select Quotes and Plan Changes.
4. Under Choose a topic, select Change cloud plan.
5. Fill in the details.

If the message box isn't visible, click on “Need more help?” to make the description field and submit button appear.

In your description, please explain the situation and include a link to this forum post so the agent has all the context.