A number of recent help calls have made it clear that anyone switching to a tablet should first line up passwords before anything else. They will be needed for these devices which relay so heavily on internet.
Even before that and before purchasing, you could download (tap or click for the iPad User Guide or the Nexus 7 User Guide), for example, and master then before going further.
Without logins and passwords very little can be done. Trying to restore them may require a major time-consuming effort which is likely to be unsuccessful anyway.
If a password cannot be recalled, then new logins and passwords should therefore be set up in advance separately. (The old ones are then just abandoned as unusable.)
Needed are Wi-Fi passwords, Email passwords, and app store passwords. Some of these may be set for you by the seller, such as Apple.
Ideally a new Gmail account should be set up to enjoy all the features offered by Google which are synchronized between devices and not available elsewhere.
Then, many apps will require their own logins and passwords.
Accounts are needed simply to identify your particular activity on the cloud. Without them you are simply locked out!
