That's a pretty broad and nonspecific request. Can you explain what you are trying to do? Keep in mind that the Certs and keys are likely referenced in up to four locations:
1) the /config directory
2) the filestore
3) the bigip.conf (which will have the path to the filestore and/or the /config directory
4) the mcpd database
To rename the files you will need to change the actual file name in the /config directory or the filestore (possibly both). You will need to change the reference pointer in bigip.conf, and then depending on how things load you may need to rebuild the mcpd database to get it to see the new filenames.
If you want to change the name on the certs and keys (for instance going from to ), then you will need to request new certs and keys from your Certificate Authority (CA).
If you can give me some more information on what you intend, I might be able to give you a better response.