Learn Swedish: Företaget gick i konkurs efter tio år. - The company went bankrupt after ten years.

Unlike in English where 'bankrupt' is an adjective, the Swedish word konkurs is a noun meaning 'bankruptcy'. The standard expression is literally 'to go into bankruptcy', which is why you must use the preposition i.

Could I use the word bolaget instead of företaget here?

Yes, bolaget would also work perfectly. While bolag strictly refers to a registered corporate entity (like an aktiebolag) and företag is a slightly broader term for any enterprise or business, they are used interchangeably in everyday Swedish.

Would it change the meaning if I wrote på tio år instead of efter tio år?

Yes, it changes the focus. Efter tio år simply places the event in time: it happened after a ten-year period had passed. Using på tio år would emphasize the duration it took for the action to be completed, translating closer to 'it took ten years to go bankrupt'.

Is there a more casual way to express that a business went bankrupt?

Yes, in spoken or casual Swedish, you will often hear the slang verb att konka. To use it in this past-tense sentence, you would simply say företaget konkade efter tio år.