Mispelt or Misspelt: How To spell?
The word Mispelt is misspelled against Misspelt, which is past perfect of "Misspell"
Misspelt has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings mi & pelt which should not be misspelled with single 'S'
Wrong Spelling:  mi-s-pelt  Correct Spelling:  mi-ss-pelt 
Find more wrongly spelled words of Misspelt to spell it well.