MIL also had to almost start over after a divorce. She divorced in her early 60's and she asked me to help her setup a 10-year plan to retirement. After the divorce she found herself owning a paid-for modest house in an area with a lower cost of living. Her retirement portfolio was around $200K. Her gross annual income was projected to be around $70K for the next 10 years and initially her annual expenses hovered around $45K per year.
The first thing we did was to cut her annual expenses from $45K to $36K. At $36K a year, once you factor in income taxes, it leaves her about $20K annually to add to her portfolio or $200K in new contributions over the next 10 year period.
So she needs $3K net per month to meet her living expenses. SS will provide about $900 a month. Her portfolio will have to generate $2,100 a month or $25,200 net per year. Assuming no income taxes (say Obama's promise to eliminate income taxes for seniors making less than $50K a year comes to pass), and assuming her portfolio has to last at least 30 years (4% SWR), it would require a $630,000 portfolio in 2009 dollars at retirement.
Note: In reality, my MIL will already be in her seventies when she starts drawing money from her retirement accounts, so she'll be able to use a higher SWR to cover her expenses. But given the OP's example (retirement at 65), I think a 4% SWR is more realistic.
So she started with about $200K and added another $200K over 10 years. So, over the next 10 years, her portfolio has to grow by $230K (in 2009 $). According to my back-of-the-envelop calculation, it would require at least a net real return of 6% a year for the next 10 years. Good luck with that!
Ideally, I would like her to cut her expenses further ($30K a year is, I think a more sustainable number for her), but she refuses to go along.
So, for someone starting with nothing, making only $50K gross and spending $36K annually, insisting on retiring at 65 without significant SS and pension benefits, the chances to pull it off are slim to none IMO.