I know that verbs which end with -ed or -d in the past and past participle are irregular. what about verbs which end with ed but with changing the root. for example try-tried -tried . notice that the letter y changed to i before adding -ed. do consider such verbs regular or irregular?
1 Verbs ending -ed or -d are considered to be regular. Generally, verbs like 'tried' are also considered to be regular, presumably because the spelling change is itself regular.
irregular verbs 
Why not take a look at this also: 
Linear Mode
