Perfective presumptive

The perfective presumptive is formed by adding to the verb stem the past participial suffix -GAN, followed by the modal particle -DIR, plus the possessive type of personal suffixes.

With the verb kelmoq, 'to come':

kelgandirmanI might have / had come
kelgandirsanYou might have / had come
kelgandirHe/she/it might have / had come
kelgandirmizWe might have / had come
kelgandirsizYou might have / had come
kelgandirlar / kelgandirThey might have / had probably come

As for the indefinite past, if the verb stem ends with -k or -g, a phonetic assimilation rule changes the suffix -GAN into -KAN (and if the verb stems ends with -g, this last consonant becomes -k).
In the same way, if the verb stem ends with -q or -g', the suffix is changed into -QAN (and if the verb stems ends with -g', this last consonant becomes -q).

The negative is formed by adding to the verb stem the suffix -MA, plus the suffix -GAN, followed by the modal particle -DIR, and then the personal suffix.

kelmagandirmanI might have / had not come
kelmagandirsanYou might have / had not come
kelmagandirHe/she/it might have / had not come
kelmagandirmizWe might have / had not come
kelmagandirsizYou might have / had not come
kelmagandirlar / kelmagandirThey might have / had not come