Common English Contractions:

 Contractions grammatically legal, but not commonly used in either speaking or writing:

• Where’d (where had)
• Why’d (why had)
• When’d (when had)
• Why’d (why would)
• What’d (what would)
• When’d (when would)

English contractions you should never use:

Amn’t (am not), Willn’t or Win’t (will not), I’s.