My website isn't loading anymore

www.vrijzinnighervormdekerknieuw-amsterdamveenoord.nl
(it is a website for a church)
So far, this is what I have done:
download the newest version 2.28, result: 1.9.4 is too old for upgrading with this installer.
Found the upgrade page and first I should upgrade to 1.10.3, downloaded the files and copied them succesfully to the site, open the upgrade page --> blank screen, opening the installer --> first page I can select the language but the next page is also blank.
What can I do? I've read somewhere that plugins can be the problem, can I turn them off in a file?
Something else?
Doing a new install is the last thing on my list, but if it comes to that, there are a lot of text on the website, what is the best way to export that from the database to normal text so I can rebuild the site?