When you goto my website, you get the following message

Fatal error: Class 'K2HelperUtilities' not found in /www/htdocs/w00d9e99/Joomla/administrator/components/com_k2/helpers/html.php on line 56

Joomla ver 2.5.28
K2 ver - 2.6.7
PHP version 5.4.45
MySQL version 5.5.46

I can log into admin site but website front page showing the error stated above.
site = pfc.renncenter-hamburg.de/

Can anyone please tell me what i can do to resolve this??

Hello,

You are using an outdated version of K2. Please update to K2 v 2.6.9

I tried to update from
k2 v. 2.6.7 to k2 v. 2.6.9 thru joomla Extension Manager but i got the following error message

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

How else can i update the k2 version

This indicates a serious site wide issue.
You can try uploading it through FTP but I would suggest addressing this issue to your hosting provider or checking the error_log for server side issues.

I uploaded the K2_6..9.zip file thru ftp to the tmp folder and then proceeded to joomla administrator and clicked on the extension manager and clicked on install from directory but still got the message

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request......

I am on a shared hosting plan and other sites are working fine. infact i have another domain under this plan and it is working fine. although it is not in joomla.

Could there be something that i am missing?? Please advice. thank you

Can you try installing another extension?

I successfully installed Akeeba backup Component .....

Clean your tmp and log folders in case some files were left there from previous installations.

I cleaned the log and tmp folder...... nothing changed...... still getting error message in front page.......
Thank you for all the suggestions.

What can i do to make this error message go and get the site back on track..

I welcome any ideas from the community please..... thank u in advance

Since you can install other extensions but you cannot update K2, i guess that this is a filesystem permissions issue . Ensure that all folders are set to 755 and all files to 644.