I have a key.ks file that needs to be opened. Can someone please suggest how to open this file in windows. Can I use Keytool command?
Yes you can, provided that it is in a format Java Keytool understands (jks,p12) and you have the password to operate on it.
The usual extension is .jks but it's not mandatory. You only have to try. Use
keytool -list -keystore [KEYSTORE_PATH_HERE]
to explore it.
Add "-v" for verbose output of the content (keys and certificates). If it's not a real Java keystore you will see an exception telling you this, otherwise it will ask for a password and if correct, it will "open" it.
This is very basic since there are many options (for example multiple password for different 'owners'). Btw, since Keytool is part of the JDK/JRE standard tools, this works on other OSes too.