YOU REMEMBER Iran, the place in the Persian Gulf that to all intents and purposes skidded off the American radar screen when the hostages were freed five months ago? It's back, at least for awhile. What's happnened is that one of the few figures who seemed somewhat reasonable and likable, if maddeningly unreliable, during the hostages crisis has been undone. That's the president, Abol Hassan Bani-Sadr, who, just before he went into hiding and possible flight abroad, was under house arrest and was facing not simply impeachment but death at the hands of a howling mob.

It is being said of President Bani-Sadr that he lacked certain political skills. A more ironic way to put it is that he had an insufficient grasp of the forces of Islamic fundamentalism. Though elected with 76 percent of the vote early in 1980, he failed to build a party or to firm up a constituency in order to contest the mosque-based machine organized by Iran's 50,000 mullahs. Nor did he manage to stay on the sweet side of his erstwhile mentor, Ayatollah Khomeini, who finally threw him to the dogs.

Such critiques may have some merit. He seemed to many Iranians, however, to be making an altogether worthwhile effort to balance the demands of Iranian tradition against the practical requirements of running a country, including fighting the war against the invading Iraqis. He also had assembled, he reported, 500 dossiers on tortue victims. That made him, by Iranian standards, a moderate. The obscurantists and zealots seem now in full command.

It matters less to most Americans now where all this will take Iran. In some quarters, there may even be a taste of grim Pleasure at Iran's deepening predicament. Yet the American interest in a stable, peaceful, prospering and, when circumstances permit, friendly Iran exists apart from the diplomatic ups and downs. Mr. Bani-Sadr was no closet pro-American. Yet he semed to have a vision of his country's future compatible with an eventual return to stability and to mutually respectful relations with the United States. Those who have forced him out seem determined mostly to devour their own revolution.