To bring a lawsuit, you need to have a claim that your rights were violated by a breach of the law, causing injury to you.
To get an injunction halting the defendant from doing something, a plaintiff must show “irreparable harm,” but the simple act of counting votes causes no harm (it’s a numerical tally) and is not irreparable (among other things, a candidate can ask for a recount).
In addition, a plaintiff must show that the “public interest” favors an injunction, an extraordinary form of judicial relief — but the public interest strongly favors counting (not disregarding) the votes of citizens relying in good faith on the law in a presidential election
Finally, a plaintiff must demonstrate that the “balance of equities” favors the plaintiff and he cannot get an injunction if he has engaged in bad conduct himself — if he has “unclean hands.” Donald Trump cannot meet this standard.