Are you in need of PFX file, or as some people will say a P12 (pkcs12).
What do you need to do to perform this convert?
First off you need Openssl. Then you need crt file and the key file.
After that is just run this command below to convert to PFX with OpenSSL
openssl pkcs12 -export -out application-company-domain.pfx -inkey application-company-domain.key -in application-company-domain.crt
If you are not sure about the password to the key file, to test the key is valid with a password you have, try this command.
openssl rsa -in application-company-domain.key
There you have some other post about OpenSSL