Problems with my WordPress account

Hello everyone,

I just noticed that I am unable to log into my old WordPress account and also a weird message now appears on my website:

Warning: “continue” targeting switch is equivalent to “break”. Did you mean to use “continue 2”? in /kunden/104158_10961/webseiten/wp-content/plugins/responsive-select-menu/sparkoptions/SparkOptions.class.php on line 778

Warning: Cannot modify header information – headers already sent by (output started at /kunden/104158_10961/webseiten/wp-content/plugins/responsive-select-menu/sparkoptions/SparkOptions.class.php:778) in /kunden/104158_10961/webseiten/wp-content/plugins/mqtranslate/mqtranslate_core.php on line 89

Apparently the problem is due to the fact that I ignored messages from my web host to upgrade to PHP 7.3.

While I am dealing with that, I am concerned that I can no longer access my WordPress account and hence to make any changes to my website. Could anyone advise me on what I should do?

Many thanks in advance for any information anyone could provide.

The page I need help with: [log in to see the link]