ても始まらない|てもはじまらない

Expresses that doing or being a certain way will not help or change the situation: “It’s no use ~.” It can lead into a suggestion to do something more constructive.

Conversational in tone, it is used when regretting or panicking will solve nothing, often before a more constructive suggestion. It is close to ても仕方がない, but emphasizes that nothing productive will come of the action or state.

• たところでN1たところで attaches to the た-form of a verb and introduces a following clause stating that the result will not change or will at best be limited, with a register that leans written. ても始まらない, by contrast, serves as the predicate that ends the sentence, leans colloquial, and is often used to advise someone to stop regretting or panicking.
• ばそれまでだN1ばそれまでだ uses ば／なら to attach to verbs, adjectives, or nouns and says that once a certain situation occurs, all previous efforts are wasted—or that a certain remark makes the topic difficult to develop further—with a neutral register. It cannot be interchanged with ても始まらない.
• としたって / としたところでN1としたって／としたところで is a hypothetical concession that can attach to verbs, adjectives, or nouns and can also indicate a person's stance, with the result stated separately in the following clause. ても始まらない attaches only to verbs and itself means 'it's no use.'
• にしたってN1にしたって is a concessive connective that can attach to verbs, adjectives, nouns, and more, and its following clause can freely express judgment, volition, or dissatisfaction. ても始まらない is a fixed expression that attaches only to verbs with the fixed meaning 'it's no use,' so the two cannot be interchanged.

ても始まらない judges an action or state unproductive; たところで and としたって / としたところで frame an “even if” condition, while にしたって can mean “even for” or “even if.” ばそれまでだ instead means that if something happens, that is the end of it.