If you are logged in as admin and
editing is on, then the login block should be showing somewhere but will just be a title with edit icons, or should be in the blocks dropdown menu. If that is definitely not happening then you may be able to manually edit the database
to add the block. I would only do this if you are sure all else has failed.
Do not do this if you are unsure about using phpMyAdmin
or do not fully understand the instructions, you will not need to delete anything so should not cause any damage.
Get a pen and paper handy and follow these steps very carefully.
1. In phpMyAdmin have a look at the table mdl_block in the name column find login, check the number in the id column and make note of it.(mdl_ is the prefix I chose when setting up moodle, your prefix may be different)
2 View mdl_block_instance table and reorder the columns based on pageid (click on the pageid column heading).
All the rows with pageid = 1 are details for blocks on the homepage. See if you have a row where blockid matches the number that was noted in step 1. If there is one make sure the visible column has 1 in it, if not then edit the row and change to 1. This should fix your problem. If not then move on to step 3 (only do step 3 if you are sure there is no row with pageid=1 and blockid the same as the value from step 1)
3. Have another look at the all the rows where pageid = 1, you should notice that there are some that have l and some that have r in the position field, these represent the blocks on the left and right of the homepage, hopefully you should also notice that in the weight column you have values ranging from 0 to however many blocks you have on that side. Make note of the highest weight value where the position is l.
4. Insert a new row in this table, do not enter a value in the id field, enter the value from step 1
into blockid, enter 1
into page id, enter course-view
into pagetype, enter l
into position, for weight enter a value 1 higher than the value found in step 3
, in visible select 1
and then put nothing in the configdata field. Save this newly entered row.
You should now have a login button on the homepage on the left hand side at the very bottom.