Q: how do i reset my restore password if i don't know it to start with?

Assuming you mean your iPhone's passcode (and not an encrypted backup password on iTunes):

http://support.apple.com/kb/HT1212

Unless you can remember the password you created to encrypt that backup, it is no longer usable.  You'll have to use a different backup.  Do you also have an iCloud backup?

Warning: Make sure it's a password you will remember or write it down for safekeeping. If you encrypt an iPhone backup in iTunes and forget your password, you can't restore from backup and your data will be unrecoverable.

If you can't remember the password and want to start again, you must perform a full software restore and chooseset up as a new device when iTunes prompts you to select the backup from which to restore.

The above comes from here:

http://support.apple.com/kb/HT4946

This article explains how to restore from an iCloud backup:

iOS: How to back up and restore your content - Support - Apple - http://support.apple.com/kb/HT1766

You asked "Can my backup be accessed through it?"

It is very likely that you never created an iCloud backup, and if that is true, the answer to your question is "No."

You would have had to go out of your way to create an iCloud backup.

Hmm, not really, to be honest.  There's a prompt in the Setup Assistant to turn on iCloud, and the default (I believe) is that iClod backup would be on.  It doesn't hurt to check.

OP, you can check for an available iCloud backup by going into Settings > iCloud > Storage & Backup > Manage Storage.  That will show you if your Apple ID/iCloud Account has a backup available.

I agree it doesn't hurt to check, and it is a simple thing to do.

But I would guess few people do both iCloud and iTunes backups, especially if they have gone to the trouble of encrypting an iTunes backup.

I agree it's unlikely.  But at this point, without an older, unencrypted iTunes backup, it's either restore as new, or check for the iCloud backup.

If there is no unencrypted iTunes backup and no iCloud backup, the OP will be starting brand new.