my website - currently unable to handle this request

Recently something went wrong with my domain hosting and the ISP had to recreate my domain again. Once it was done I copied back my codeigniter website but since then I am getting the following error  message - examprep.co.ke is currently unable to handle this request. HTTP ERROR 500.

 Could someone assist me please.

check the error log

Dear Paradinight,

Thanks for the quick response. Kindly guide me on how to check on the error log. I still learning .........

Do you have ssh?