كان لازم اغير اللمبة لانه ما كان في ضو بالغرفة.

In Levantine, لازم means must / have to / necessary. Very often, speakers add كان before it to put the obligation in the past:

• لازم اغير اللمبة = I have to change the bulb
• كان لازم اغير اللمبة = I had to change the bulb / I needed to change the bulb

So كان here shifts the idea into the past.

اغير means I change or, in context, I change/replace.

It comes from the verb غيّر = to change.
This is the first person singular imperfect form:

• بغيّر = I change / I am changing in everyday present
• اغير = often used after things like لازم, بدي, ممكن, etc.

So after لازم, Levantine commonly uses this form without بـ:

• لازم اغير = I have to change
• not usually لازم بغيّر

اللمبة is a very common Levantine word for the bulb / the lamp, borrowed historically from European languages.

In everyday speech, اللمبة usually means the actual light bulb or sometimes light/lamp depending on context.

Other words exist, but اللمبة is extremely natural in spoken Levantine.

لانه means because.

It is made up of:

• لـ = for / because of
• أنه / انو = that

So literally it developed from something like because that..., but in modern usage you can just treat لانه as because.

In Levantine pronunciation, you may also hear:

• لأنه
• لانو

All are connected to the same idea, and لانو is especially common in speech.

Here في means there is / there are.

So:

• في ضو = there is light
• ما في ضو = there isn’t light
• ما كان في ضو = there wasn’t light

This is a very common Levantine existential structure:

• في = there is/are
• ما في = there isn’t/aren’t
• كان في = there was/were
• ما كان في = there wasn’t/weren’t

Because this is how past negation works in this structure.

• كان في = there was
• ما كان في = there wasn’t

Here:

• كان marks the past
• ما negates it

So the phrase is not word-for-word English, but the whole chunk ما كان في should be learned as a very common way to say there wasn’t.

ضو means light.

It is very common in Levantine speech. You can think of it as the everyday spoken word in many contexts.

نور also means light, but the two are not always interchangeable in every expression. In this sentence, ضو sounds very natural:

• ما كان في ضو بالغرفة = There wasn’t any light in the room

So yes, they are related in meaning, but ضو is a very normal spoken choice here.

Because بـ is the preposition in / at / with, and it often attaches directly to the following noun.

So:

• غرفة = room
• الـغرفة = the room
• بـ + الـغرفة = بالغرفة = in the room

This attached form is extremely common in Arabic writing and speech.

Arabic does not always use the in the same way English does.

Here ضو is being used in a general sense:

• ما كان في ضو بالغرفة = there wasn’t light in the room
• very naturally translated as there wasn’t any light in the room

So Arabic does not need الضو here. Using the bare noun is normal.

A natural pronunciation would be something like:

kaan laazem ghayyir il-lambe laanno maa kaan fii dawo bil-ghurfe

Some notes:

• كان = kaan
• لازم = laazem
• اغير = ghayyir or 2ghayyir depending on how you write the initial hamza
• اللمبة = il-lambe
• لانه = laanno / la2anno / laano
• في = fii
• ضو = daw / dawo depending on region and style
• بالغرفة = bil-ghurfe

Pronunciation varies by country and speaker, but this gives a good Levantine feel.

Because in Levantine, the taa marbuuTa ending ـة is usually pronounced as -e or -a in pause, often -e in many Levantine varieties.

So:

• غرفة is often pronounced ghurfe
• not classical-style ghurfah

That is very typical of spoken Levantine.

Yes, but the meaning changes in time.

• ما في ضو بالغرفة = There isn’t any light in the room
• ما كان في ضو بالغرفة = There wasn’t any light in the room

So the version in your sentence matches the past situation and explains why the speaker had to change the bulb.

In this context, it most naturally means change/replace the light bulb.

Because the next part says there was no light in the room, listeners will understand اللمبة here as the bulb that needed replacing.

So while اللمبة can sometimes be interpreted more broadly as lamp/light, context makes bulb the best reading here.