IT IS TROUBLING that Indira Gandhi could be reelected to parliament in India barely 20 months after she was ousted as prime minister for her gross abuses of power. She has never apologized for depriving India of democracy during the period of her "emergency" rule in 1975-77. As the winner now in a contest that Prime Minister Morarji Desai made a test of his own prestige, and as the presumptive leader of the opposition, the redoubtable Mrs. Gandhi, still only 60, is in a position to do him - and India - much harm.

How did she win? Most accounts point out that she chose as her comeback launching pad a remote rural state, one lightly touched by the crudities of "emergency" rule and one already safely controlled by her Congress I (for Indira) party. Her new constituency is a thousand miles (and a dialect) away from the one in northern India that knew and rejected her last year. It is said to be one of the few that actually profited from the social benefactions in whose name she had grabbed personal power. She also was able to make hay out of the difficulties of Mr. Desai, an octogenarian who has managed to keep together the coalition that elected him but whose stewardship has otherwise been lackluster.

We of the West have a certain tendency to personalize Indian politics - to identify Mrs. Gandhi with authoritarianism and Mr. Desai with democracy. One wonders, however, if the Indian people are so devoted to the forms of democracy that they are willing indefinitely to overlook inadequate leadership. Perhaps this is another way of asking whether India is, in the last analysis, governable at all. But it says something that Mrs. Gandhi was returned to parliament from a state that as prime minister she served well.

In parliament she will have a forum and the opportunity to capitalize on Mr. Desai's failings, real and imagined - and, not incidentally, the chance of working to quash the prosecutions still pending against her from the emergency period. Few close students of the Indian scene deny that she could return to power, especially if the relative buoyancy created by the new good harvest lets down. India's democracy was tested 20 months ago. It remains under challenge.