Portal broken and no spare flint and steel? Tough luck, prepare to live out in the nether for the rest of your life. The end. At least you’ll have the Nether Update to keep you engaged, though hydration and sleeping might be a problem in the land of fire and lava. Please share if this has helped you. On a serious note though, you have plenty of options…
If your portal is missing obsidian for some reason, find some in chests in bastions or fortresses. Or barter with piglins for it (more on that below).
Lure a ghost or blaze
This one’s simple. Carefully lead a ghast to the portal by letting it follow you. Then, let it shoot at the portal frame with its fireball to relight it! Blazes also work, though that way is usually harder (for obvious reasons).
Lead fire to the portal
Requirements: wood OR nether wood
A nether portal will relight if a neighbouring block is on fire. If you have wood, simply lead fire to the portal frame by making it spread along a trail of wood. This may be easier done with a bucket, as you can place lava right near the portal. It might take a while for the portal frame to relight.
If you don’t have wood, cut down warped and crimson wood, which are fire resistant… but can be crafted into crafting tables which will catch on fire!
Get a fire charge item
1. Mine nether gold ore and barter with piglins. There’s a roughly 8% chance of them giving a fire charge in return. Remember to wear at least one piece of golden armor when bartering to prevent piglin hostility! OR
2. Craft a fire charge from one blaze powder + coal + gunpowder. Get blaze powder from blazes. Coal from wither skeletons (or charcoal in a furnace instead). And gunpowder from ghast drops.
3. Use the fire charge on the portal frame to relight it.
Craft a flint and steel
You could craft a new flint and steel. Two ingredients, seems simple enough. The flint is the easy part – you’ll find plenty of gravel patches dotting the nether. The iron is harder to get in the nether though.
1. Look for iron ingots in loot chests in bastions and fortresses. OR
2. Craft a furnace from cobble (or find black stone or deep slate in the nether instead). Use wood or crafting tables from nether wood as fuel (nether stem logs by themselves are fire resistant).
3. Next, smelt down iron gear and weapons into nuggets, you’ll need 9 for an iron ingot. Look for skeletons with iron gear for drops. Normal skeletons will spawn in the soul sand valleys, and have a 20% chance of spawning in a fortress.
Take a swim in lava
If you have nothing to lose, simply skip all the guides and respawn! Place all you belongings in a chest (can be crafted from nether wood), and take a warm bath in lava. You could also drop your items, although consider this note from the Minecraft wiki regarding item despawning;
“Items despawn after 6000 game ticks (5 minutes) of being in a loaded chunk. The 5-minute timer is paused when the chunk is unloaded.”