Cannot log in to nextcloud or panel

Hi.
After an upgrade last year, I was never able to to get back into the “panel” (:4443) as it forgot my password.
Quite recently I can no longer get into Nexcloud at all (I don’t know when this happened as it was a friend who was downloading from his home that emailed me with the bad news).

Everyone gets:

Error
Your data directory is invalid
Ensure there is a file called “.ocdata” in the root of the data directory.

I managed to ssh into the pi and do a sudo ncp-config.
It starts up happily, but usually ends with:

n unhandled exception has been thrown:
Exception: Environment not properly prepared. in /var/www/nextcloud/lib/private/Console/Application.php:164
Stack trace:
#0 /var/www/nextcloud/console.php(99): OC\Console\Application->loadCommands(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#1 /var/www/nextcloud/occ(11): require_once(‘/var/www/nextcl…’)
#2 {main}warning: No domain found. Defaulting to ‘nextcloudpi’
Your data directory is invalid
Ensure there is a file called “.ocdata” in the root of the data directory.

Is this a difficult thing to do?
Is my data directory root /var/www/nextcloud ?

So nc-info gives this:

Running nc-info
Gathering information...
NextCloudPi version  v1.50.3
NextCloudPi image    NextCloudPi_12-20-19
OS                   Raspbian GNU/Linux 10. 5.10.103-v7+ (armv7l)
automount            yes
USB devices          sda 
datadir              /var/www/nextcloud/data
data in SD           yes
data filesystem      ext2/ext3
data disk usage      14G/29G
rootfs usage         14G/29G
swapfile             /var/swap
dbdir                /var/lib/mysql
Nextcloud check      error
HTTPD service        up
PHP service          up
MariaDB service      up
Redis service        up
HPB service          down
Postfix service      up
Internet check       ok
public IPv4          212.159.102.81
public IPv6          not found
Port check 80        closed
Port check 443       closed
IP                   192.168.1.80
gateway              192.168.1.254
Interface            eth0
certificates         alistairscloud.org
NAT loopback         no
Uptime               52min

You say I can put logs and stuff into the paste bin… How do I do that?
You would need to tell me the terminal commands to do that.
Sorry!