Structure of Negative sentence in simple present tense is as follows

Doer of actionનથી (nathI)Verb + Suffix
હું (huM)નથી (nathI)કરતો (karato)

Suffix depends on gender rather than person (first, second or third)

Suffixes are as follows

English PronounGujarati PronounSuffix
Masculine Singular

Pronouns

I, You, He,

This, That
હું (huM), તું (tuM),

આ/એ/તે (A/e/te)

પુલ્લિંગી
તો (to )
Feminine Singular & Plural
Pronouns

I, You, She,

This, That

("we(feminine)" not included)
હું (huM), તું (tuM),

આ/એ/તે/ તેઓ (A/e/te/teo)

સ્ત્રિલિંગી
તી (tI )
Neuter Singular

Pronouns.

Generally only in

third person

It, This, That
આ/એ/તે (A/e/te)

નપુસકલિંગ
તું (tuM )
Masculine Plurals in all

persons

We, You(plural),

They, Those
અમે (ame),

આપણે (ApaNe),

તેઓ/આ /એ/તે
(teo/A/e/te)

તમે (tame)
તા (tA)
We (feminine)

Neuter Plural
(They/Those )
or group of different genders
અમે (ame),

આપણે (ApaNe),

તેઓ/આ /એ/તે
(teo/A/e/te)

તમે (tame)
તાં (tAM)

Forms follow pattern discussed in ઓ-ઈ-ઉં-આ-ઈ-આં (o-I-uM-A-I-AM ) યો-ઈ-યું-યા-ઈ-યાં ( yo-I-yuM-yA-I-yAM ) rule

Examples

(If a boy says) I do not speak -> હું નથી બોલતો (huM nathI bolato)

(If a girl says) I do not speak -> હું નથી બોલતી (huM nathI bolatI)

We do not speak -> અમે/આપણે નથી બોલતાં (ame/ApaNe nathI bolatAM)

(If said to a boy) You do not play -> તું નથી રમતો (tuM nathI ramato)

Tree does not move -> ઝાડ નથી હલતું (jhAD nathI halatuM)

You(plural) do not dance -> તમે નથી નાચતાં (tame nathI nAchatAM)

They/Those do not keep-> એ/તેઓ નથી મુકતાં (e/teo nathI mUkatAM)

Listen examples in this lesson at

Negative sentence simple present tense in Gujarati