Q. Unicorn BS6 starts only in neutral, when we try to start in in 1st gear, it doesn't work. Is it normal?

If you mean it isn't starting when it's in gear with the clutch disengaged, and it used to start under those conditions, check to see if there's a pin switch on the clutch lever housing that's gotten stuck. If so, then the starter won't be able to tell you've got the clutch lever pulled and will refuse to start. You should be able to fix it by spraying some light lubricant (like WD-40 or a silicone-based lube) down the shaft of the switch. Don't use anything heavy like white lithium grease.

If you mean it isn't starting when it's in gear with the clutch disengaged, and it used to start under those conditions, check to see if there's a pin switch on the clutch lever housing that's gotten stuck. If so, then the starter won't be able to tell you've got the clutch lever pulled and will refuse to start. You should be able to fix it by spraying some light lubricant (like WD-40 or a silicone-based lube) down the shaft of the switch. Don't use anything heavy like white lithium grease.

No, it's not normal, there is a problem with your bike.