How do I get past login in start up?

As suggested, you COULD just reinstall the SD card and start anew. But you lose all the modifications you did to your SD card. On the other hand, starting fresh with a modern distribution can be good too.

Before wiping the card, you can backup your data. If the 'pi is your only Linux machine, you are probably better off getting a second SD card and then mounting the original SD card in an USB reader.

But, contrary to what was said above, you can hack yourself back into your 'pi.

Use a computer to mount the SD card. The computer will probably be Windows (which I don't have).

You can then edit the file "commandline.txt" or "cmdline.txt" (you'll recognize it when you see it). If there is an "init=...." there, change it to "init=/bin/sh". If you don't see any "init=" in that file, add it at the end (init=/bin/sh).

Now you can boot, and will get a VERY basic raspberry pi up and running. And you're logged in as root. Issue:

  mount / -o rw,remount

and then edit /etc/shadow . Now, for the "pi" user (probably the bottom one) remove everything starting with $6$ ending just before the : (and then a number).

You'll probably end up (barring typos):

  pi::15536:0:99999:7:::

Save the file. Then:

  mount /dev/mmcblk0 /boot

and edit /boot/cmdline.txt Restore the original configuration. Save it.

Type

  cd /

  umount /boot

  sync

  mount / -o remount,ro

  sync

and then powercycle your 'pi. It should come up again, but now without a password for the user pi. Add one again asap.....

As suggested, you COULD just reinstall the SD card and start anew. But you lose all the modifications you did to your SD card. On the other hand, starting fresh with a modern distribution can be good too.

Before wiping the card, you can backup your data. If the 'pi is your only Linux machine, you are probably better off getting a second SD card and then mounting the original SD card in an USB reader.

But, contrary to what was said above, you can hack yourself back into your 'pi.

Use a computer to mount the SD card. The computer will probably be Windows (which I don't have).

You can then edit the file "commandline.txt" or "cmdline.txt" (you'll recognize it when you see it). If there is an "init=...." there, change it to "init=/bin/sh". If you don't see any "init=" in that file, add it at the end (init=/bin/sh).

Now you can boot, and will get a VERY basic raspberry pi up and running. And you're logged in as root. Issue:

  mount / -o rw,remount

and then edit /etc/shadow . Now, for the "pi" user (probably the bottom one) remove everything starting with $6$ ending just before the : (and then a number).

You'll probably end up (barring typos):

  pi::15536:0:99999:7:::

Save the file. Then:

  mount /dev/mmcblk0 /boot

and edit /boot/cmdline.txt Restore the original configuration. Save it.

Type

  cd /

  umount /boot

  sync

  mount / -o remount,ro

  sync

and then powercycle your 'pi. It should come up again, but now without a password for the user pi. Add one again asap.....