1. You must become a jedi-knight of white-board programming. For this, go to HackerRank and work absolutely as many problems as you can. But don't program them in an editor, get a whiteboard and use that. Then type in the program when you are ready to get it graded.
2. You need to fill in some knowledge you would have gotten in college. For this, read the first few chapters of "Introduction to Algorithms" by Cormen, Leiserson, Rivest, and Stein.
There's no royal road. Treat this as your full-time job until you get a job, i.e. work on it 8-10 hours a day 5 hours on the weekend.
This is what I did last time I was laid off.....I got nothing for 6 months, then after 6 weeks of the above regime I was able to slam dunk every interview I went to and got an awesome offer. Best of luck.