Negative sentence in past continuous tense very easy to create from corresponding positive sentence.

Positive sentence structure is

Doer of actionverb + ઈ(I) Form of રહેવું
(“rahevuM”)
Form of હોવું
(“hovuM”) as in Past Tense
અમે (ame)કરી (karI)
રહ્યાં(rahyAM)
હતાં(hatAM)

In negative sentence, we use negative form of હોવું (“hovuM”).

Doer of actionverb + ઈ(I) Form of રહેવું
(“rahevuM”)
NEGATIVE Form of હોવું
(“hovuM”) as in Past Tense
અમે (ame)કરી (karI)રહ્યાં(rahyAM)નહોતાં(nahotAM)

Refer previous lesson Negative sentence in simple past tense for NEGATIVE Form of હોવું (“hovuM”)
https://learnmarathiwithkaushik.com/courses/negative-sentence-in-simple-past-tense-in-gujarati/

Position of negative form of હોવું (“hovuM”) can be before or after Form of રહેવું (“rahevuM”)

Examples

(If a boy says) I was doing :- હું કરી રહ્યો હતો(huM karI rahyo hato )
(If a boy says) I was not doing :- હું કરી રહ્યો નહોતો (huM karI rahyo nahoto )

(If a girl says) I was doing :- હું કરી રહી હતી (huM karI rahI hatI )
(If a girl says) I was not doing :- હું કરી નહોતી રહી (huM karI nahotI rahI )

(To a girl) You were laughing :- તું હસી રહી હતી (tuM hasI rahI hatI )
(To a girl) You were not laughing :- તું હસી રહી નહોતી (tuM hasI rahI nahotI )

Tree was moving :- ઝાડ હલી રહ્યું હતું ( jhAD halI rahyuM hatuM )
Tree was not moving :- ઝાડ હલી રહ્યું ન હતું ( jhAD halI rahyuM na hatuM )

My teeth were moving :- મારાં દાંત હલી રહ્યાં હતાં ( mArAM dAMt halI rahyAM hatAM )
My teeth were not moving :-મારાં દાંત હલી નહોતાં રહ્યાં ( mArAM dAMt halI nahotAM rahyAM )

He(polite form) was coming :- તેઓ આવી રહ્યા હતા (teo AvI rahyA hatA )
He(polite form) was not coming :- તેઓ આવી રહ્યા ન હતા (teo AvI rahyA na hatA )

Listen examples in this lesson at

Negative Past continuous tense in Gujarati