Internal Server Error

i keep getting Internal Server Error

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

Please contact the server administrator and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.”

can you please tell me what i need to do step by step, pretty please? it used to work like a month ago but now it’s not working.

my site has the following settings:
upload_max_filesize 32M
post_max_size 33M
max_execution_time -1
max_input_time 60

https://www.ads-software.com/extend/plugins/wp-all-import/