Reissued SSL certificate but doesn't have .key file

Question

The issue I'm having is reinstalling an SSL certificate purchased through Namecheap.
When I purchased the certificate, I received a .zip file with these files:

• domainname.ca-bundle
• domainname.crt
• domainname.p7b

When trying to install the SSL certificate, on an apache2 server using SSH, it was originally configured to use a .key file. I have tried modifying the certificate to use p7b but this generates an error.
Here is the code:

SSLEngine on
 SSLCertificateFile /var/www/domainname/public_html/domainname.crt
 SSLCertificateKeyFile /var/www/domainname.ca/public_html/domainname.p7b
 SSLCertificateChainFile /var/www/domainname.ca/public_html/domainname.ca-bundle

What modifications or changes must I make in order to install this SSL Certificate?
Thanks for any help or assistance in this matter, been trying to fix this for a while!

Answer 1

I looked up some openssl commands to compare the .key and .cert file to make sure they matched. It was indeed the incorrect .key file and I managed to find the correct key to install it correctly. Thank you for your helpful advice and here is the source I used for the commands: https://www.ssl.com/faqs/how-do-i-confirm-that-a-private-key-matches-a-csr-and-certificate/ In case this helps someone else with the same issue. – RichardManson 3 hours ago