Here is nothing "apparently", please provide more information. From where did you get this information, is the name of your fiscal year correct, what is the exact error message?

I got this info from here (Is this the correct way to re-open a closed fiscal year?) on this forum:

https://www.odoo.com/nl_NL/forum/help-1/question/is-this-the-correct-way-to-re-open-a-closed-fiscal-year-52028

First I activated the developers mode,

Then I tried to put this instruction in 

Accounting / end of period / cancel closing entries

Then: Edit action

in General Settings; View Ref.

I clicked on the arrow to get access to:

account.open.closed.fiscalyear.form

In architecture I pasted the above instruction under

<?xml version="1.0"?>

I get this error:

ValidateError Field(s) `arch` failed against a constraint: Invalid view definition Error details: Specification mandate value for attribute account_fiscalyear, line 2, column 26

I hope this is more clear for you?

I am not at all familiar with programming language.

My database in online.

Can I acces it myself then?

If so, Can you explain a little more how to do?

Thanks

My database in online.

Can I acces it myself then?

If so, Can you explain a little more how to do?

Thanks

Pretty sure not. You should revert to Odoo support then. Or another solution would be to create a database backup, download it, manipulate it and restore it again. If you do not know how to manipulate the database, you should seek for professional help, because you'd install and set up Postgres before you can start manipulating a database. That's far beyond the scope of this forum.