There are no direct flights to Bhutan from Bangalore. You have to fly to Delhi or Kolkata or Guwahati then on catch another flight to Bhutan. Paro is the main airport of Bhutan.
No tour operator is currently operating to Bhutan I believe.
Maybe COVID travel restrictions are laid. Can you check with travel agencies. If possible call the airlines directly and speak. They might help u
You can go by road also via Bagdogra - Siliguri - Jaigaon - Phuentsholing (Border Town of Bhutan).
It’s plain road upto border town of Bhutan but thereafter it’s all Ghat Road but not all that difficult (we seniors toured Bhutan this route). Though no visa is required for Indians but take note of entry formalities in Bhutan (consult some travel operator).
By Air: While there are no Bangalore to Bhutan direct flights, for anyone looking to fly to Bhutan, they can do so from Delhi, Kolkata or even Guwahati to Bhutan's main airport, Paro. People from Bangalore can travel to any of the above destinations to grab a flight to Paro to enter and enjoy the mountainous country.