"I do not feel cold."

Translation: मुझे ठंड नहीं लगती है।

[LinguisticBoi]

Hey is there a difference between सर्दी, ठंड, and ठंडा?

[PraharPandya]

सर्दी is the winter season or cold illness.
ठंड is cold temperature, noun.
ठंडा is cold temperature, adjective masculine. ठंडी is feminine adjective.
सर्दी के मौसम में ठंडा खाने से या ठंडी कुल्फी खाने से सर्दी ज़ुकाम हो जाता है।
Eating cold food or cold kulfi (a type of icecream) in winter gives you cold (सर्दी ज़ुकाम is normally used to avoid confusion both words meaning cold as far as I know).
Just an example not a fact.

[LinguisticBoi]

And, I assume गर्मी has similar usage to सर्दी (summer season), while of course गरम and ठंडा have similar usage (hot vs cold). Is there a "hot" equivalent of ठंड (a noun meaning hot temperature)?

[PraharPandya]

That would just be गर्मी. ठंड लग रही है, गर्मी लग रही है।

[NupurBalas]

Why is I sometimes "mein" and in this case "mujhe"?

[Deen926665]

Mujhe means (to me)

For example:

Raj mujhe yek kaamij detha hei
(Raj gives me a shirt) it means raj gives it - to me (mujeh)

You can not use "mein" instead of "mujhe" here,
if you so it means "Raj gives 'I' a shirt"

No sense right?

The same way - someone feels cold but not "me". (not to me)

So we should use "mujhe" rather than "mein"

[Tanya209986]

Why do we not end this sentence with hooh?

[PraharPandya]

हूं means am to be used with मैं not मुझे. e.g.,
I am not shivering with cold: मैं ठंड से काप नहीं रहा हूं।

[GabrielBou109736]

Can't the sentence begin with ठंद since it is the subject?

[Robertium]

I used the male form of the verb (लगता) and it marked it wrong. Is it?

[LinguisticBoi]

Yes. The word ठंड is feminine. Think of the sentence as meaning "The cold is not felt by me" (hence मुझे being oblique). Anyways, it doesn't matter what your gender is, it'll always be लगती because ठंड is feminine.